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Section 1. GUIDELINES FOR READING ACADEMIC TEXTS

MAKING INFERENCES AND UNDERSTANDING INDIRECT INFORMATION GIVEN IN THE TEXT

INFERENCE AND PURPOSE QUESTIONS

Instruction: There are questions that require you to make inferences. The answers to these questions are not directly provided in the passage—you must «read between the lines.» In other words, you must make conclusions based indirectly on information in the passage. Many text-readers find these questions the most difficult type of reading questions.

Inference questions may be phrased in a number of ways. Many of these questions contain some form of the words infer or imply.

Purpose Questions ask why the author of a text mentions some piece of information, or includes a quote from a person or a study, or uses some particular word or phrase.

Text: The Chemistry of Cleaning Clothes Sample item:

Part 1. Have you ever wondered how a cup of detergent cleans soiled jeans, towels, socks, and other articles in your wash, or how cleaning fluid at the dry cleaner whisks away that grease stain from your suit? And why are hair spray, vinegar, club soda, and baking soda surprisingly effective dirt and stain removers in an emergency? The answers lie both in the chemical properties of various types of dirt and stains and in the ways that the cleaning agents chemically interact with them.

It can be inferred from this passage that

Hair spray, vinegar, club soda, and baking soda are detergents.

A cup of detergent cannot clean in an emergency/

Cleaning fluid can remove a grease stain but cannot remove dirt.

Cleaning agents interact with chemical properties of dirt and stains..

Choice (A) is not a valid inference; because hair spray is a cosmetic product while vinegar, club soda, and baking soda are mostly used as food products.

Choice (B) also cannot be inferred; as the word cup is used in the meaning

«any quantity». Besides the use of a detergent doesn’t depend on degree of emergency.

Nor can (C) be inferred; because the notion of grease stains and dirt is used as a whole.

Since every substance has chemical properties, it can be inferred that the essence of cleaning is in the interaction of cleaning agents with chemical properties of dirt and stains. Therefore choice (D) is the right inference.

Part 2. Dirt and stains typically consist of particles, such as minerals from soil, protein and other organic matter from living things, or bits of black carbon. The particles are trapped on cloth fibers by grease and oil, which cannot be dissolved in water. Anything that can loosen the grease and oil from the fibers and disperse (scatter) these substances in the wash water or dry-cleaning solution will remove the dirt and stains.

Soaps, detergents, cleaning fluids, and many emergency stain removers are effective cleaners because they can dissolve and emulsify (break up and suspend) the oil and grease that holds dirt in place. The grease and trapped soil particles then can be carried away in the water or dry-cleaning solution. But these agents differ widely in t

heir dirt-fighting activities and the conditions under which they work. To understand why, we must understand the chemical nature of soaps and detergents.

The words soap and detergent are often used interchangeably, but the two cleaners differ considerably. Soaps are generally made from natural fats and oils. Soaps are excellent for cleaning our hands, face, and body, because the loosened dirt is rinsed away immediately. But soaps have definite drawbacks for cleaning laundry. For example, soaps often allow dirt lifted from clothes to re-deposit on the clothes before the wash cycle is finished. And in hard water (water containing high levels of minerals), soaps react with minerals to form scum, called soap curd. Soap curd does not dissolve. It is difficult to remove from fabrics, and it makes the fabric feel stiff.

Because of these drawbacks, laundry soaps have largely been replaced by detergents. Detergents are synthetic (artificial) mixtures of ingredients that not only clean clothes but also prevent re-deposition of dirt, discourage scum formation, and possess other useful properties. The most important advantage of detergents is the ability to clean effectively in hard water.

Sample Questions:

Which of the following can be inferred from the passage?

(A) Particles of minerals, black carbon, and organic matter trapped on cloth fibers by grease and oil can be dissolved in the water.

(B Particles of minerals, black carbon, and organic matter trapped on cloth fibers by grease and oil can be loosened from the fibers and dispersed in the wash water or dry-cleaning solution.

Which of the following would be the most reasonable guess about drawbacks of laundry soaps?

Soaps aren’t effective cleaners because they cannot break up and suspend the oil and grease that holds dirt in place.

Soaps can loosen dirt if it is rinsed away immediately.

Soaps react with minerals in hard water.

Soaps make the fabric feel stiff.

Which of the following would be the right guess about laundry soaps?

Soaps re-deposit dirt on the clothes before the wash cycle is finished

Soaps form soap curd with water.

Soaps clean our hands, face, and body but soaps cannot be used for cleaning laundry.

Soaps are generally natural mixtures while detergents are artificial mixtures.

Does the passage imply that soaps mostly have drawbacks while detergents mostly have advantages?

Sample answers:

It can be inferred from the passage that . . .

The author implies that . . .

The author suggests that . . .

It is probable that .

Part 3. Both soaps and detergents contain cleaning ingredients known as surfactants. Surfactant compounds are molecules (linked groups of atoms) attracted to the boundary between two liquids that normally do not dissolve in each other, such as oil and water. One end of the surfactant molecule is attracted to water but not oil, and the other end is attracted to oil but not to water.

This dual nature of surfactant molecules boosts the «wetting» ability of water. This means that water containing surfactants can more easily penetrate and disperse dirt and stains. One end of the surfactant molecule dissolves and emulsifies the grease that traps soil particles on fabrics. The other end dissolves in the surrounding water. As a result of this action, one portion of the molecule pulls away from the other, and this force pulls the grease from the clothes and suspends it in the form of tiny droplets. Washing machine agitation also helps loosen the greasy soil. After the soil droplets are suspended in the water, the thin layer of surfactant molecules around them keeps them separated from the fabric and prevents them from resettling on the clothes. The suspended droplets and the soil clinging to them are then easily rinsed away by the water.

The same principle enables hair spray to remove ink and certain other stains from clothes. Some hair sprays contain alcohol, which behaves chemically in a way similar to surfactants in detergents. One portion of the alcohol molecule penetrates and emulsifies the oils that hold the ink pigments in place. Another portion of the alcohol molecule dissolves in the alcohol solvents also found in hair spray. In this way, hair spray loosens the ink pigments, which can then be removed by conventional laundering with water and detergents.

Purpose Questions

These questions ask why the author of a passage mentions some piece of information, or includes a quote from a person or a study, or uses some particular word or phrase.

Sample item:

Question: Why does the author mention surfactants?

Answer: The author refers to surfactants to indicate that soaps and detergents must contain these ingredients in order to do the cleaning.

Sample Questions

  • · Why does the author mention the «wetting» ability of water?
  • · Why does the author refer to one end and the other end of the surfactant molecule?
  • · Why does the author mention hair spay?
  • · Why does the author use the phrase «dual nature of surfactant»? Why does the author describe the molecular activity of surfactants?

Sample Answer Choices:

The author refers to /

The author describes /

The author uses the phrase /

The phrase proves that /

The phrase is mentioned to illustrate that

to indicate that

to strengthen the argument that to provide an example of

to challenge the idea that to contradict

to support the proposal to to illustrate the effect of

to make it easy for the reader to understand how

Part 4.

  • · 4-1. Compounds called enzymes enhance the cleaning action of surfactants. Enzymes are complex molecules made by living organisms. Often called «biological catalysts,» enzymes promote certain chemical reactions without themselves being changed. Enzymatic action is similar to digestive juices in the stomach, which break down food in preparation for digestion in the intestines. Detergent enzymes, made by bacteria in factory production vats, react with and break up stains that are made of proteins. Such stains include blood, meat gravy, milk, eggs, and grass. Enzymes break down these substances into simpler forms that can be removed by other components in the detergent.
  • · 4-2. If you’re out of enzyme detergents and the stores are closed, try using a meat tenderizer on a protein stain. The tenderizer contains enzymes intended to partially digest proteins in meat before it is cooked. But when poured onto clothing or carpets, the enzymes can also break up protein molecules in stains. (But make sure to rinse the stain with water to wash away the salt, spices, and coloring that are included with the enzymes in the tenderizer.)
  • · 4-3. Another group of chemical compounds used in detergents are called builders. Builders typically make up more than half the weight of a box of detergent. Their principal function is to soften hard water. These chemicals react with and remove from wash water certain minerals, particularly those containing calcium and magnesium. Such minerals can react with surfactants to form scums that deposit on clothes and interfere with cleaning action. Minerals can also promote redeposition of removed soil particles.
  • · 4-4. Another function of builders is to make the wash water alkaline. Alkali builders are chemicals that neutralize acids in the water and aid the breakup of oil and fat molecules by rupturing their chemical bonds. Some builders act as buffering agents to maintain the proper alkaline level in the wash water.
  • · 4-5. Because ordinary baking soda contains an alkali — sodium bicarbonate
  • · baking soda is handy for neutralizing and removing acid stains such as those made by toilet-bowl cleaners. Because vinegar contains acetic acid, which is mildly acidic, it is useful for breaking up and dissolving such alkaline stains as hard-water residues. You also could use club soda on these residues, because it contains weakly acidic carbonic acid, a compound not found in plain water.
  • · 4-6. Some builders also boost the action of surfactants. For example, certain builders help surfactants suspend loosened dirt and keep it from settling back on clothes. Other builders help surfactants emulsify greasy soil by breaking the oily particles into tiny globules.
  • · 4-7. In the 1960’s, chemicals called phosphates were the most common builders in detergents. Phosphates remove minerals from hard water by combining with them. The compound thus formed is then rinsed away with the water after the clothes are washed.
  • · 4-8. But phosphates in waste water were found to harm the environment. Detergent phosphates ultimately ended up in streams and lakes, and because phosphates are nutrients for algae, the chemicals overfertilized the streams and lakes. club soda on these residues, because it contains weakly acidic carbonic acid Eventually, the abundance of algae clogged streams and lakes, setting in motion a process that could kill most of the life in the water. Because of this, detergent manufacturers drastically reduced the phosphate content of their products and began using builders that were less harmful to the environment.

Valid inferences based on sentences

To identify inferences based on sentences read each sentence, then mark the one answer choice—(A), (B), or (C)—that is a valid inference based on that sentence.

Sentence: Enzymatic action is similar to digestive juices in the stomach.

Valid inferences: (A) Enzymes break down food in the intestines. (B) Digestive juices are enzymes that break down bacteria. (C) Enzymes like digestive juices promote certain chemical reactions.

Sentence: But make sure to rinse the stain with water to wash away the salt, spices, and coloring that are included with the enzymes in the tenderizer.

Valid inferences: (A) Tenderizers have to be separated from water. (B) Enzymes have to be separated from tenderizers. (C) Enzymes have to be separated from salt, spices, and coloring.

Sentence: These chemicals react with and remove from wash water certain minerals, particularly those containing calcium and magnesium.

Valid inferences: (A) Builders react with wash water. (B) Builders contain calcium and magnesium. (C) Builders remove calcium and magnesium.

Make valid inferences based on the following sentences:

Alkali builders are chemicals that neutralize acids in the water and aid the breakup of oil and fat molecules by rupturing their chemical bonds.

Certain builders help surfactants suspend loosened dirt and keep it from settling back on clothes.

Detergent phosphates ultimately ended up in streams and lakes, and because phosphates are nutrients for algae, the chemicals overfertilized the streams and lakes.

Valid inferences based on longer passages.

Read the passages. If the statements following the passages are valid inferences based on passages, mark the items TRUE. If the statements cannot be inferred from the passage, mark those FALSE.

Passage 4-5. Because ordinary baking soda contains an alkali — sodium bicarbonate — baking soda is handy for neutralizing and removing acid stains such as those made by toilet-bowl cleaners. Because vinegar contains acetic acid, which is mildly acidic, it is useful for breaking up and dissolving such alkaline stains as hard-water residues. You also could use club soda on these residues, because it contains weakly acidic carbonic acid, a compound not found in plain water.

Valid inferences: (A) Baking soda, vinegar and club soda are similar in their effect on stains. (B) Baking soda, vinegar and club soda can be used both on alkaline and acidic stains. (C) Each of these — baking soda, or vinegar, or club soda can be used in their own way.

Passage 4-7. In the 1960’s, chemicals called phosphates were the most common builders in detergents. Phosphates remove minerals from hard water by combining with them. The compound thus formed is then rinsed away with the water after the clothes are washed.

Valid inferences: (A) In the 1960’s, chemicals called phosphates were used as building materials. (B) In the 1960’s, chemicals called phosphates were used as detergents for washing clothes. (B) In the 1960’s, chemicals called phosphates were used as parts of detergents.

Part 5.

  • · 5-1. Interestingly, there is no relationship between a detergent’s sudsing action and its cleaning ability. Nevertheless, manufacturers may recommend the use of low sudsing detergents for front-loading tumbler-type washing machines because high levels of suds would cushion clothes as they drop back into the water after being lifted out in the tumbling action. Such a cushioning effect would interfere with the machine’s washing action. To appeal to consumers who prefer various amounts of suds, detergent manufacturers include in their formulas special sudsing modifiers. These compounds are long-chain molecules, made from natural fats, that can either boost or depress levels of suds made by dissolved detergents.
  • · 5-2. Bleaches do not remove dirt particles but make them colorless or nearly colorless. Liquid chlorine bleach is the most powerful of the chemical bleaches used, as laundry aids. Chlorine bleach not only whitens clothes, but also disinfects and deodorizes them. It can, however, remove color from clothes. A less powerful chemical bleach is oxygen bleach. Because it is safe to use on most fabrics, oxygen bleach is the one most frequently added to detergents. It is also used in presoak products to aid in cleaning heavily soiled clothes or in helping to remove stubborn stains before clothes are put through a normal washing machine cycle. Some presoak products use enzymes, but these require more time to work than do products using only oxygen bleach. Also, enzyme presoak products should not be used at the same time as chlorine bleach, because chlorine bleach destroys enzymes. By using the products separately, you will get the maximum benefit of each.
  • · 5-3. Other laundry aids also do not remove dirt or stains, yet they can make clothes appear cleaner. Whiteners, also known as optical bleaches, consist of organic (carbon-containing) molecules that can absorb invisible forms of light and,through a complex process at the atomic level, reemit it as visible blue light. Clothes treated with these compounds come out of a wash looking both brighter and whiter than they did before being washed. The hydrogen peroxide found in many medicine cabinets for the treatment of wounds behaves comparably to the bleach we add to washes. When applied to blood stains, for example, peroxide liberates oxygen atoms, which turns red blood pigments into less brightly colored stains. Denture cleaning tablets, which contain oxygen in the same form found in oxygen bleaches, can similarly decolorize stains made by tea and coffee.
  • · 5-4. Unfortunately, laundry cleaning agents function only in water, a medium that can damage some natural fabrics, such as silk and wool, which are water-sensitive. When they are wet, water-sensitive fibers swell in diameter and shorten, causing the garment to shrink. The most effective way of removing dirt and stains from water-sensitive articles is dry cleaning. Dry cleaning is a process in which a liquid other than water is used to dissolve and flush away oil and grease along with underlying soils. The most useful solvents in dry cleaning are water-insoluble liquids derived from petroleum, particularly a carbon-and chlorine-containing compound called perchloroethylene. Dry-cleaning solvents, unlike water-based detergents, do not repel oil and grease molecules. Instead, the solvents surround and dissolve these molecules. Many commercial dry cleaners also add special detergents to their solvents to further loosen soil particles.
  • · 5-5. A primitive form of dry cleaning is possible using vegetable shortening as a «solvent.» The shortening dissolves oils — for example, those in deep-fried snacks or those that hold ink pigments in place. Then a follow-up treatment with hair spray will remove the dissolved oils and pigments. So, the next time you’re studying late on a Sunday night, and your pen slips from the paper onto your white pants, where a greasy snack fell without your knowing it, remember your chemistry. A little shortening and hair spray could prevent an ugly stain. [Gordon Graff]

Answering inference and purpose questions. Making valid inferences based on sentences. Making valid inferences based on longer passages.

Which of the following can be inferred from passage 1?

A detergent’s sudsing action and its cleaning ability are closely connected.

Manufacturers may recommend the use of low sudsing detergents for top-loading tumbler-type washing machines?

Consumers prefer various amounts of suds.

Detergent manufacturers are sudsing modifiers made from natural fats.

Which of the following would be the most reasonable guess about bleaches in passage 2? .

If the statements following passage 2 are valid inferences, mark the items TRUE. If the statements cannot be inferred from passage 2, mark those FALSE.

Bleaches are a kind of detergents.

Liquid chlorine bleach is a less powerful chemical bleach than oxygen bleach.

Oxygen bleach is weaker then liquid chlorine bleach.

Liquid chlorine bleach is safe to use on most fabrics.

Enzyme presoak products should be used at the same time as oxygen bleach.

Use bleaches and presoak products separately.

Answer inference and purpose questions. Make valid inferences based on passages 2-5.

Does passage 2 imply that bleaches are better or worse than presoak products?

What does the author refer to in passage 3 sentence: «Clothes treated with

these compounds come out of a wash looking both brighter and whiter than they did before being washed.»

Does he mean that clothes should be treated before being washed, after being washed or in the process of washing?

Why does the author use the phrase in passage 3: «The hydrogen peroxide

found in many medicine cabinets…»?

Why does the author state in passage 4 that laundry cleaning agents function only in water?

Does the author imply in passage 5 that dry cleaning is better than laundry cleaning?

Can it be inferred from passage 5 that you can do without detergents to

remove stains?

If so, what sentence or sentences in this passage prove it?

Section 2. GUIDELINES FOR GRAMMAR TEST

Adjective/adverb errors

The most common type of word form problem involves the use of an adverb in place of an adjective or an adjective in place of an adverb. A few points to keep in mind:

Adjectives modify nouns, noun phrases, and pronouns. Adjectives often come before nouns:

an important test a quiet evening a long letter They often answer the question What kind?

She is a brilliant doctor. (What kind of a doctor is she? A brilliant one.) Adjectives also follow the verb to be and other linking verbs.

The glass was empty. That song sounds nice. They look upset.

Adverbs may modify verbs, participles, adjectives, prepositions, adverb clause markers, and other adverbs:

Ann eagerly accepted the challenge, (an adverb modifying the main verb accepted)

It was a rapidly changing situation, (an adverb modifying the present participle changing)

She wore a brightly colored scarf, (an adverb modifying the past participle colored)

Ted seemed extremely curious about that topic, (an adverb modifying the adjective curious)

We arrived at the airport shortly before our flight left, (an adverb modifying the adverb-clause marker before)

We arrived at the airport shortly before noon, (an adverb modifying the preposition before) The accident occurred incredibly quickly, (an adverb modifying the adverb quickly)

Sometimes adverbs are used at the beginning of sentences, usually followed by a comma. These adverbs sometimes modify the entire sentence rather than one word in the sentence:

Generally, I like my classes.

Usually, Professor Ingram’s lectures are more interesting.

Most adverbs tested in this section are adverbs of manner. They are formed by adding the suffix -ly or -ally to an adjective:

quick quickly, comic comically, comfortable comfortably, historic historically. Adverbs of manner answer the question How?

She treated her employees honestly. (How did she treat her employees? Honestly.)

A few adverbs (fast, hard, high, for example) have the same form as adjectives:

He bought a fast car. (adjective)

He was driving so fast that he got a speeding ticket, (adverb)

Well is the irregular adverb form of the adjective good.

Juan is an exceptionally good student. He did very well on the last test.

Some adjectives also end in -ly: friendly, yearly, costly, and lively, for example. That was a costly mistake.

Errors with comparatives and superlatives

Most adjectives have three forms: the absolute (the basic adjective form),

the comparative, and the superlative.

Comparatives are used to show that one item has more of some quality that another does.

George is taller than his brother.

Superlatives are used to show that one item in a group of three or more has the greatest amount of some quality.

He was the tallest man in the room.

Let us explain how comparatives and superlatives are formed:

One-syllable adjectives: warm –warmer — the warmest

Two-syllable adjectives ending with –y: funny funnier — the funniest

Other two-syllable adjectives: common more common — the most common

Adjectives with three or more syllables: important — more important — the most important

Some two-syllable adjectives have two correct forms of both the comparative and the superlative: narrow — narrower/more narrow — narrowest/most narrow; clever — more clever — cleverest — most clever; polite — more polite — politest — most polite.

A «negative» comparison can be expressed with the words less and least.

Less and least are used no matter how many syllables an adjective has. less bright less expensive

the least bright the least expensive

The absolute form of a few adjectives ends in -er (tender, bitter, slender, clever, and so on.) Don’t confuse these with the comparative forms (more bitter or bitterer, for example).

Many adverbs also have comparative and superlative forms. The comparative and superlative forms of all -ly adverbs are formed with more and most.

more brightly more importantly

most brightly most importantly

A few adjectives and adverbs have irregular comparative and superlative forms:

Irregular Comparatives and Superlatives: good/well — better — the best; bad/badly — worse — worst; far — further — the farthest/the furthest.

Mini-test

Identify and correct adjective/adverb errors

Surprising, baking soda is an effective dirt and stain remover.

Cleaning agents interact chemically with various types of dirt and stains because of their chemically properties.

Particles are typically for composition of dirt and stains.

Soaps and detergents are often interchangeable, though they differ most considerable.

Generally, soaps are made from naturally fats and oils.

Curd is difficulter to remove from fabrics, and it makes the fabric feel more stiff.

The two liquids dissolve in each other most normal.

Often called «biologic catalysts», enzymes promote certainly chemical reactions.

I read in a weekly magazine that club soda contains weakly acidical carbonic acid.

Interesting, liquid chlorine bleach is the most powerfulest of the chemical bleaches.

Clothes come out of a wash looking both more brighter and more whiter than they did before being washed.

Oxygen atoms turn red blood pigments into less brighter colored stains. Many commercial dry cleaners also add specially detergents to their solvents.

I don’t like studying lately on a Sunday night. The colder the air the least moisture it can hold.

High humidity makes us feel uncomfortable hot and sticky.


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