OG12 30

Kath1985

For members of the seventeenth-century Ashanti

nation in Africa, animal-hide shields with wooden

frames were essential items of military equipment, a

method to protect warriors against enemy arrows and

spears.

?? (A) a method to protect

?? (B) as a method protecting

?? (C) protecting

?? (D) as a protection of

?? (E) to protect

答案C
想請問
(1)E為何不對?
(2)A、B、D各錯在哪?

mudiduange

这个是典型的状语考点，LZ可以查查资料
AB：shields怎么能是一个方法呢？逻辑不对
D:as在这里明显是连词，但后面跟的又不是句子，错误
E：不定式可以做主语，同样这个也不是完整的句子。而且不定式放句首，在GMAT题目还没有出现过是对的情况

lonelyorchid

楼上的解释完全正确。
补充两点，
首先：GMAT里没有能够指代整句的代词，所以必须用现在分词做状语的方式来修饰整个句子。
其次：as不一定非要做连词，表因果。但是如果不做连词，则as做介词，引导后定，但是问题是后定一般需要紧跟先行词。这里离得太远了……

牛津高阶：
as  

preposition, adverb, conjunction

preposition
used to describe sb/sth appearing to be sb/sth else: They were all dressed as clowns. ◆ The bomb was disguised as a package.
used to describe the fact that sb/sth has a particular job or function: She works as a courier. ◆ Treat me as a friend. ◆ I respect him as a doctor. ◆ You can use that glass as a vase. ◆ The news came as a shock. ◆ She had been there often as a child (= when she was a child).

adverb
as ...as ... used when you are comparing two people or things, or two situations: You're as tall as your father. ◆ He was as white as a sheet. ◆ She doesn't play as well as her sister. ◆ I haven't known him as long as you (= as you have known him). ◆ He doesn't earn as much as me. ◆ He doesn't earn as much as I do. ◆ It's not as hard as I thought. ◆ Run as fast as you can. ◆ We'd like it as soon as possible.
used to say that sth happens in the same way: As always, he said little. ◆ The 'h' in honest is silent, as in 'hour'.

conjunction
while sth else is happening: He sat watching her as she got ready. ◆ As she grew older she gained in confidence.
in the way in which: They did as I had asked. ◆ Leave the papers as they are. ◆ She lost it, just as I said she would.
used to state the reason for sth: As you were out, I left a message. ◆ She may need some help as she's new.
used to make a comment or to add information about what you have just said: As you know, Julia is leaving soon. ◆ She's very tall, as is her mother.
(written) used to say that in spite of sth being true, what follows is also true