树木生长的速度被认为是地球上太阳黑子周期最可靠的迹象之一the rate at which trees grow is believed to be among the surest indications of sunspot cycles.
(A) among倒装，主语应该是the rate，所以应该用单数is。
(B) among倒装，主语应该是the rate，所以应该用单数is；tree应该用复数，使未划线部分的their有 一致的指代对象。
(C) on earth 放置句首修饰整个句子，不符合逻辑；their 的指代存在歧义，离它最近的是 sunspot cycles，未划线部分的 as seen 应该要紧跟其修饰的名词。
(D) tree应该用复数，使未划线部分的their有一致的指代对象；谓语结构不完整，应该用is believed被动语态。
(E) 正确，on Earth修饰indications，主语是the rate，谓语动词用单数is。
ACDE看起来都像有歧义会修饰到Jupiter，但是ABE有as…as硬伤，因此只能在CD当中选。而，which更容易理解成就近修饰，而且用法还错了，如果修饰jupiter的话要用circles；而circling可以看作也是massive planets的修饰成分，与most of them共同修饰massive planets
D.E，mostly作为副词，“主要地，通常地，多半地”，prep07上的解释是修饰错误，以为副词不能修饰名词
C.circling在这里不存在伴随的歧义，伴随一般是指伴随动作，因为本句唯一的句子是天文学家detected...，若认为伴随是不可的，逻辑主语就成了astronomers，逻辑错误；此处circling作定语修饰Jupiter.
另外可用固定搭配排除，as large as or larger than = at least as large as
choice a the comparison made in choice a is ok. the real problems with choice a:
- 'the ratio of 42 times' is redundant; it'd be good enough just to say '42 times'. note that the word 'ratio' is not redundant in choices c-d, since it's being used as a modifier to make a logical connection.
- it doesn't say 42 times what. not only is that unacceptably vague, but it also breaks parallelism.
choice b is badly worded: 'compares to 42 times in 1980' seems to say that, on forty-two different occasions in 1980, the ceo:blue-collar ratio reached 419:1. this is not what we are trying to say.
more generally, when speaking about ratios as is done here, you can't just write "42 times" by itself. it has to be 42 times something. sometimes you can use pronouns - the height of the sears tower is more than four times that of the statue of liberty - but you can't use empty space.
choice c exhibits proper usage of 'times' followed by their pay. it also uses the ratio, a correct identification of exactly what is being described.
the construction in choice e doesn't make sense.since that's obviously not the case here——the report points out a fact about these CEOs, not the identities of the CEOs themselves。
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。
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一、必错
1.having done和having been done都不是动名词结构，因此不能充当名词成分！
所以SC中，如果这两个结构做主语、宾语等，必错！
2.having done和having been done做后置定语，必错！
having done做后置定语，一般都要改成相应的定语从句
having been done做后置定语，一般都要改成相应的done做过去分词，或者改成定语从句
3.having done和having been done用于“with独立主格”中必错！
指with+sb/sth+having done/having been done这种情况
二、可用但一定要慎用
做状语
having done和having been done都可以做伴随状语，并不是必错。但一定要注意，句子中明确地有“现在完成时”这种意思时，才可以这么用，否则基本都错。