D: as the poster above was trying to explain, "work at xxxxx" is not an idiomatic expression here.
even if you don't know this, though, you should still be able to pick (a) over (d), because (a) is more direct and efficient in its language.
i.e., even if (d) were idiomatic (it isn't), it would still be inferior to (a):
works ... at the prevention of X
vs.
prevents X
there's no question which of these has greater economy of expression.
- 'scale of' doesn't make sense
- you can't say 'each that had...' (can't follow 'each' with a relative pronoun - if you're going to use a relative pronoun, it has to come directly after the thing it's trying to modify)
- no justification for using the past perfect ('had been') - that verb, if there's a verb there at all, should be in the simple past (the same tense as everything else in the sentence, because everything described in the sentence is contemporaneous)
- it doesn't make sense to use 'each' AFTER the comma, because it's not true that each structure was connected with a road system. instead, the road system connected all of the structures with each other, which is nowhere close to the same thing. (having 'each' BEFORE the comma makes sense, because it's actually true that each of the structures comprised up to 600 rooms.)
analogy:
the USA comprises 50 states, each of which is united by a federal government --> wrong (the implication is that each state has its own federal government)
the USA comprises 50 states, all of which are united by a federal government --> correct
the USA comprises 50 states, (all) united by a federal government --> correct, whether you have 'all' or not
A，A: Initiated five centuries [ after Europeans arrived in the New World on Columbus Day 1992 ] --> 表示1992加上五个世纪才是initiate的时间（加五百年都到未来去了），此时after后面做时间状语
"evidence to suggest" and "evidence that suggests" are both acceptable in this sort of context. neither is a basis for elimination.
normally you would see "evidence that suggests..."
however, they've used "evidence to suggest..." here, in order to avoid writing evidence THAT suggests THAT xxxxx. not because it's wrong -- just because it's ugly.
数字之间的比较用greater不用more，数字只有大小没有多少 B错误
未划线部分是单数，they 不正确，排除CD
所以主句是讲G差点灭绝，后面讲它现在的数量是以前DDT时期的5倍。这个语意有转折，不能用缺乏转折连词的伴随状语/独立主格
E：“now with numbers five times greater than” does NOT modify the idea of "surviving a close brush with extinction"; instead, it is a much later situation, far removed from (and in considerable contrast to) the near-extinction. Therefore, a modifier is inappropriate here; a separate clause, written in a different tense (as in the correct answer), is a better solution.
capability to do;GMAT认为capability of X-ing/in X-ing是wordy/awkward的。
ability：sb&aposs ability to do sth或ability of sb/sth to do sth
capability to do不如ability to do简洁，但不可就此判错。
be able to do
be capable of doing
have ability to do ; ability of sb. to do
have capability to do doing ; capability of sb. to do doing
划线部分身后的同位语从句that the bank's loans will help foreign producers compete with American businesses应该修饰的对象是concern，即，是担心贷款帮助了外国的商业。因此，该同位语从句应直接放在concern身后，不能放在passage身后。
seem, appear, look是表象系动词，可以直接作be动词使用，表示是，如：
She didn't appear surprised at the news at all.
此外还有固定搭配：appear to be/to have been，it appears that，如：
She appeared to be in her late thirties. 看样子她快四十岁了。
It appears that there has been a mistake. 看来有一个差错。
what是个名词，可以替换成the thing，what appears to be ……，看上去是……的东西
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D: as the poster above was trying to explain, "work at xxxxx" is not an idiomatic expression here.
even if you don't know this, though, you should still be able to pick (a) over (d), because (a) is more direct and efficient in its language.
i.e., even if (d) were idiomatic (it isn't), it would still be inferior to (a):
works ... at the prevention of X
vs.
prevents X
there's no question which of these has greater economy of expression.