1.Engraving is a process which the surface of metal is first covered with an acid and then inscribed with some sharp instrument.

2.For many years ago much of what was possible to know was derived from inspiration or divination and did not involve the rational process of reasoning in wide use today.

3.Ayn Rand, ______ novels deal with the nature of capitalism in a democracy, is often taught in introductory courses in economics.?

of many whose?

whose many of?

whose of many?

many of whose

4.The formation of a rainbow occurs a process in which light is diffused at varying rates by the surrounding atmosphere resulting in the reflection of different wavelengths of light.

5.Though difficult, it possible for an adult learner of a new language to master the subtleties of the grammar and syntax of the new language.

6.When a bird molts, ______ loses its feathers, it is actually preparing itself for the regeneration of the lost feathers.?

so its?

as if?

as when it?

so that

7.The scientific method is a system which a problem or challenge is identified and possible solutions are created and tested, with the final results evaluated to determine the best approach to the resulting theory.

8.The Smithsonian Institution in Washington D.C. is home to the largest collect of Native American artifacts in the United States most of which remain uncatalogued and hidden from public view.

9.Many modern critics of American literature have called Mark Twain, born Samuel Clemens, ______ .?

as America's greatest writer?

was America's greatest writer?

America's greatest writer?

to have been America's greatest writer

10.In the modern era, face-to-face communication is becoming near as uncommon as hand-written letters.

讲解：

1.A This is a hard one to explain because we need to understand several different things about English grammar insgroupsto be able to choose the right answer. In a nutshell, we need a preposition here between the with the head noun and the sentence the surface of metal is first covered with an acid and then inscribed with some sharp instrument.

In other words, the sentence that comes from the adjective clause would look like this:

The surface of metal is first covered with an acid and then inscribed with some sharp instrument in [this] process.

2.Correction: years

Generally speaking, we have two choices here:

for many years

or

many years ago

In other words, we cannot use for and ago together.

Want to know why? Sure you do! It's simple!!

When we have a preposition and a noun together, we have a prepositional phrase. A prepositional phrase is actually one kind of adverb phrase. Are you still with me? We're almost there! So, when we use for and many years together, we have an adverb phrase, right? Right!! Now, ago is an adverb, right?? Right! Therefore, it is redundant (unnecessary) to use ago with the prepositional phrase. Easy, right??? Right!!

3. D Question focus: Correct usage of whose and adjective clauses with quantifiers.

In this question, we want to talk about many of Ayn Rand's novels in the adjective clause. So we have several things happening at once in this question. First, we are are talking about Ayn Rand's, not Ayn Rand. When we need to use the possessive form in an adjective clause, we have to use whose. Next, we need to use a quantifier to talk about a certain portion of the novels. The proper way to use quantifiers is to use the quantifier with of.

4 Correction: occurs in

This one is easy to explain: occurs is an intransitive verb, so it cannot be followed by a noun. When we see this kind of problem on the TOEFL, we can often add a preposition.

5. Correction: it is possible

This one is easy to explain: We are missing the main verb in this sentence. We can add is and everything is fine!!

6. C.Question focus: Subordinate clauses and adverb clauses.

If we look at everything in this sentence, we will notice that we have a verb, loses, that does not have a subject. This is the only answer choice with a subject.

Still confused? Okay, in this sentence as is a preposition. Since every preposition must be followed by a noun (called its object), we need to have an object for the preposition. In this case, we have a noun clause as the object of the preposition.

You might still be confused. I explained this one to my students by telling them that as means the same thing (or almost the same thing) as like or for example. 7. Correction: in which

We need to understand adjective clauses and prepositions for this question. Essentially, we need a preposition here because the head noun, system, can go into the adjective clause like this:

A problem or challenge is identified and possible solutions are created and tested in [this] system.

8. Correction: collection

Finally! An easy one to explain. We need a noun here (because we are talking about the largest collection of Native American artifacts); collect is a verb.

9.C Question focus: Transitive verbs.

TOEFL loves this kind of question!!

This one is tricky because have called requires an object and a complement. Usually TOEFL likes to use call with two nouns after it. This is what I tell my students: call + two nouns.

So, in this sentence, we have a simple sentence like this:

... critics... have called Mark Twain... writer

We have two nouns: Mark Twain and writer for the verb have called.

10 Correction: nearly

We need to use nearly, which means almost, to modify as uncommon as. near, on the other hand, is a preposition and must be followed by a noun.