限定与非限定的问题，愁死了！！

152. When the technique known as gene-splicing was invented in the early 1970's, it was feared that scien­tists might inadvertently create an "Andromeda strain," a microbe never before seen on Earth that might escape from the laboratory and it would kill vast numbers of humans who would have no natural defenses against it.

(A)  it would kill vast numbers of humans who would have no natural defenses against it

(B)  it might kill vast numbers of humans with no natural defenses against it

(C)  kill vast numbers of humans who would have no natural defenses against it

(D) kill vast numbers of humans who have no natu­ral defenses against them

(E)  kill vast numbers of humans with no natural defenses against them

呵呵。。。其实不用这么苦恼，最简单的方法是，用排除法，把明显错误的选项一个一个地去掉，剩下的就是正确的了。此法易学易用，老少咸宜，童叟无欺，屡试都爽啊。

关于此类问题，以前CD上有过很多的总结，我将某位牛人的总结列于下，供大家参考：

（1）that定语从句: 限定性（紧跟被修饰词后面）

（2）由前面没有逗号的一wh开头的词(who, which...)引导的定语从句，限定性

（3）with短语作定语: 限定性

（4）wh系列定语从句: 非限定性（前面有逗号或是介词）
       （5）现在分词定语: 非限定性

1.He asks the girls who is in red clothes to form a team.
2.He asks the girls with red clothes to form a team.
3.He askes the girls, who is in red to form a team.
4.He askes the girls, dressing in red clothes to form a team.

1,2句是限定的，可以想象成体育馆中有一大群女孩儿，有穿红的，穿绿的，有黄的等等，这群女孩子中穿红的那一部分组成一个队。此时这个穿红的修辞成份是对女孩子的群体起限定作用，是局部概念。

3，4句是非限定的，可以想象成体育馆中有一大群女孩子，所有的女孩子一个不落地组成一个队，这些女孩子共有一个特点，全都是穿红的。此时穿红的修辞成份是对女孩子的群体不作限定，只表示这一个群体的特点。

There is the only one Tananmen Square on earth. Do we still need to specify which one we refer to? A non-attributive clause works fine with this condition.

Suppose there are two bridges in a city. If you say something about one of them, then it calls for an attributive clause. The clause actually signals the readers that there are more than one bridge in the city.

Attributive /non-attributive clauses are defined in terms of grammar, but they do deliver some semantic meanings to the readers.

Using a non-attributive clause the writer is trying to make a strong argument. It might reflect the confidence of him; he might have some hard evidence to support his opinion.

Another e.g.

1) I hate all the politicians who are always nasty. ( you are not attacking all the politicians; you only refer to some of them)

2) I hate all the politicians, who are always nasty. ( basically, you challenge all the politicians )

141:应该少了个逗号吧

非限定性定语从句，其作用为：对所修饰的成分作进一步的说明，它与主句用逗号隔开

Unless the transplant involves identical twins， who have the same genetic endowment

152 all choices are restrictive: not all humans, but rather part of humans who....

同意orange，从简单明确的下手，限定不限定可以不优先考虑

OG11TH SC-7:

Carnivorous mammals can endure what would otherwise be lethal levels of body heat because they have a heat-exchange network (which kept) the brain from getting too hot.

A. which kept
B. that keeps
C. which has kept
D. that has been keeping
E. having kept

The answer is B, there is no doubt about it.

Then, OG says: The two underlined words contain two separate errors. The pronoun (which) introduces ***nonrestrictive*** clauses, which include information relevant but not critical to an understanding of the sentence.  The pronoun (that) introduces a restrictive clause, which is critical to understanding the sentence because the clause defines its antecedent.  Here, the clause following (which) defines heat-exchange network, so (that) must be used in place of (which).  The use of the past tense (kept) is incorrect because a current situation is discussed; the present tense (keeps) is consistent with the other verbs in the sentense.

B Correct. (that) introduces a restrictive clause; (keeps) indicates a current situation and is consistent with the other verbs in the sentence.

按ＯＧ的意思是：

which是非限定性？that是限定性？这怎么理解呢？／／

OG11TH SC-7:

这里说如果是which的话定语从句的主语很可能是Carnivorous mammals ，但是原句的定语从句的主语必须是network。 所以这里用了that做限定定语从句。

而在一般情况下，which也可以使用，只是需要碰到的问题是A的那个定语从句使用了过去时，这个时态不对。

我不认同楼上的观点

OG11明确指出了，限定性的定语从句用that不用which引导，非限定的用which不用that,否则错。这是个correctiveness的标准。

ring-cheng姐姐　　　找到一例：

199. Because the Earth's crust is more solid there and thus better able to transmit shock waves, an earthquake of a given magnitude typically devastates an area 100 times greater in the eastern United States than it does in the West.>>

(A)  of a given magnitude typically devastates an area 100 times greater in the eastern United States than it does in the West

(B)   of a given magnitude will typically devastate 100 times the area if it occurs in the eastern United States instead of the West>>

(C)  will typically devastate 100 times the area in the eastern United States than one of comparable magnitude occurring in the West>>

(D)  in the eastern United States will typically devastate an area 100 times greater than will a quake of comparable magnitude occurring in the West>>

(E)   that occurs in the eastern United States will typically devastate 100 times more area than if it occurred with comparable magnitude in the West>>

At issue is the accurate expression of a complex comparison. Choice D, the best answer, presents the proper form of comparison, will typically devastate an area 100 times greater than will; thus, choice D logically indicates that earthquakes in the eastern United States are 100 times more devastating than are western earthquakes. Choices A, B, and E use it incorrectly to suggest that the same quake strikes both the eastern and the western United States. In choice C, 700 times the area... than is unidiomatic.

答案是Ｄ为什么这里的occurring in the West不是就近修饰呢？／？