08语法笔记中as的用法不懂

Dreamcatcher999

有一个关于As的问题：下面这道题是08语法笔记中的题目，为什么在OG的解释中，答案B & D的as是incorrect的?

例:OG10-39 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

OG10-39 的解释(注意 C 选项的解释):
Choice C is best because the participle protecting begins a phrase that explains what the shields did. Choices A and B awkwardly use the singular word method to refer to items of military equipment rather than to the use of such items. Also, a method of protecting would be more idiomatic than a method to protect in A or a method protecting in B. In B and D, as is incorrect; also, a protection in D has no noun for which it can logically substitute. Choice E is incomplete; used to protect would have been acceptable.
OG11-24 的解释(注意 C 和 E 选项的解释)

Logical predication + rhetorical construction

The underlined part of the sentence begins a phrase describing items of military equipment. It is awkward and inaccurate to describe items as a method. Replacing the underlined phrase with the participle protecting creates a modifying phrase that clearly explains the purpose of the items of military equipment.

A  A method to protect is an awkward reference to items

B  The singular a method should not refer to the plural items, as a method protecting is not idiomatic

C  Correct. In this sentence, protecting properly introduces a modifying phrase revealing the purpose of

the items.

D  Beginning the phrase with as is incorrect; using the noun form protection creates wordiness

E  The infinitive to protect cannot act as an adjective modifying items; the participial form of the

verb, protecting, is required

The correct answer is C.

yxlrei

错误答案的错法可以有很多种
这题应该不难排除as : animal hide shields can NOT be "a method" or "a protection".

"The use of" animal hide shields can be "a method" or "provide protection"...

Dreamcatcher999

yxlrei 发表于 2015-8-29 21:45
错误答案的错法可以有很多种
这题应该不难排除as : animal hide shields can NOT be "a method" or "a prot ...

OG的意思好像是as不能这样用，为什么不能用as呢?
我能明白您的意思， 只是对as用法不了解

Dreamcatcher999

yxlrei 发表于 2015-8-29 21:45
错误答案的错法可以有很多种
这题应该不难排除as : animal hide shields can NOT be "a method" or "a prot ...

OG的意思好像是as不能这样用，为什么不能用as呢?
我能明白您的意思， 只是对as用法不了解