"being" in (a) is not only unnecessary, but also not used idiomatically.
in general, "being" can be used in some instances where you're talking about X (specific) being a Y (general).
for instance, jake did not enjoy being a graduate student.
notice that the GENERAL category - graduate student - follows "being". the SPECIFIC (jake) doesn't.
you can't do this in reverse.
this choice tries to use the specific (the particular concern) after "being", rather than the general category (an obstacle to congressional passage). regardless of whether the usage of "being" is appropriate otherwise (which, here, it isn't anyway), you can't do that.
(b) breaks up "a concern" from "that the bank’s loans will help...". once that modifier is divorced from "a concern", it is no longer clear exactly what is the concern.
also, "a concern" is problematic. since the sentence cites one very specific concern, it should say "the concern".
(d) first, there's a change in meaning by setting "an obstacle to congressional passage" off in commas. It makes it a nonessential modifier, but this fact is necessary to the meaning of the sentence. the core of that clause becomes "legislators cite the concern" and we lose the important "as an obstacle" piece.
second -- look at the placement of the modifiers.
"that the bank's loans with..." should immediately follow "the concern", since that is what it modifies.
similarly, "as an obstacle..." should be as close as possible to "cite", because that's what it modifies.
in the correct answer, both of these modifiers are placed immediately next to the things that they're supposed to modify; in (d), both constructions are needlessly separated.
(e) the problem with (e) is"it". it's not ambiguous, though; it actually doesn't refer to anything at all. there's no noun in there, anywhere, to which "it" can refer.
("Ambiguous", in reference to pronouns, is used to refer to a pronoun that has 2 or more possible antecedents, not to refer to a noun that has no possible antecedent.)
嵌入式关系分句：有一种关系分句(即定语从句)，它既是先行词的后置修饰语(即定语)，同时又是另外一个分句结构的宾语(即宾语从句)
In his breastpocket he had a patch of scarlet, which I suppose was the paper cap serving as a handkerchief.
还原进定语从句并补全省略部分，则有：
I suppose (that) patch of scarlet was the paper cap serving as a handkerchief.
注意理清语义，本题的宾语应是statements about an opponent 而不是opponent！
即：A recent poll of elected officials suggests that candidates, when in the midst of a tough campaign, often make statements about an opponent that they may not think are true.
最近一项对当选官员的民意调查显示，在激烈的竞选中，候选人往往会发表自己可能认为不真实的关于对手的言论。
Remember—Step One of ANY sentence correction problem is "Figure out the exact intended meaning."
The easiest way to gauge whether you're doing Step One well enough is to see what happens when you have to make decisions involving meaning.
If you have to figure out the meaning in retrospect--AFTER noticing a split--then that's a failure of Step One.
In other words, when you encounter a split that depends on context, you should already be aware of the EXACT intended meaning of the relevant words. Meaning is not the kind of thing that you should have to "go back and figure out".
• If you encounter a pronoun in any answer choice, you should already know what it's meant to stand for. You should not have to go back to figure that out.
• If you encounter a modifier, you should alredy know what it's meant to describe. Shouldn't have to go back.
• If you see the second half of a parallel structure (e.g., "... and xxxx"), you should already know what the first half is. Shouldn't have to go back.
This might seem demanding, but it really isn't--it's just normal reading. I.e., not strange "academic" reading, but rather the kind of reading you'd do for pleasure.
If you were reading a book and came to a sentence with a description (= a "modifier"), then you would absolutely know what it was describing! (And if you didn't, you wouldn't keep reading until you'd thought it through.)
Step 1 is actually just like reading a book or magazine. Not "academic" at all.
the "with" modifier is attached directly to the old animal (the one from which the elephant is descended). that's not the intended message of the sentence: the sentence is meant to describe the evolution of the elephant's trunk, not some earlier animal's trunk.
the -ING modifier is also troublesome, because -ING modifiers adopt the timeframe of the clause to which they are attached. the problem here is that we need to change the timeframe: "the elephant is descended..." is stated in the present, because it's a timeless fact about evolution, but "its trunk originally evolved..." needs to be in the past because it's an isolated historical event. the -ING modifier mistakenly suggests that both of these belong to the same timeframe.
in any case, all three of the following are legitimate:
evidence to suggest...
evidence that suggests...
evidence suggesting...
you will never have to choose between two choices that are fully correct; if you see 2 legitimate versions of some idiom, then something will be wrong elsewhere in one of the choices.
"has descended" means "has moved downward". this can be in either a literal sense (he has descended to sea level from a height of 8000 feet) or a metaphorical sense (i don't want to descend to the level of common street thugs), but it can't refer to ancestry.
if you mean to discuss ancestry, which is clearly the case here, then you must use "is descended".
"is descended from" is indeed a description of a condition in the present. it's the same thing as "is a descendant of".
e.g. my friend is a direct descendant of George Washington.
you wouldn't say "was", unless my friend is dead.
same thing with the elephant - if you write "the elephant was..." in this case, you are actually implying that the elephant is extinct.
B：
- sentence fragment (there's no main subject, and/or no main verb: the whole thing is one big whether X or Y construction, which can't stand alone as a sentence)
- 'whether or not' is wordy (yes, that's enough to kill this answer choice all by itself) on the GMAT, whether or not is considered redundant.
Eliminate B, C and E.
- change in meaning: the way this is written, it's the status quo that is affecting the U.S., whereas the sentence is supposed to say that the decision (whether Taiwan will do blah blah blah) is what will affect the U.S.
D:
- the pronoun 'it' doesn't have an antecedent. there are certain idiomatic constructions in which a standalone 'it' is allowed (such as 'make it difficult to...'), but this isn't one of them.
- bad parallelism: 'will develop' is in the future tense, but 'preserves' is in the present tense. as they are alternatives in a decision, these must be presented in the same tense.
If whether is used to connect two verbs/actions, I'd keep it simple and just analyze all such situations with "or" as the parallel marker.
--
If whether is used to connect two nouns, THEN I'd consider both "whether" and "or" as parallel markers.
E.g., Everyone in the country, whether civilian or soldier, was in danger during the war.
(A) I can’t complain about this one. “Carbon dioxide gas” is a singular, non-countable noun, so “less” works fine as a modifier. And this part is a little bit tricky, but the second part of the sentence refers to several different “gasses” – a countable, plural noun – so “fewer” is appropriate.
The phrase beginning with “that” (“that have been implicated…”) correctly modifies “other gasses.” It’s also completely fine to use the “-ing” form of the verb after “as well as.”
So we’ll keep (A).
(B) It’s a funny quirk of English: if “as well as” were changed to “and” then we’d want the verbs “burn” and “emit” to be in parallel form. But since we have “as well as”, we’re better off using “emitting”, as we did in (A).
More importantly, I can’t make any sense of the “having been” at the end of the underlined portion. For that reason, we can scrap (B).
(C) You could argue that the pronoun “they” is ambiguous here, since it could refer to “diesel engines” or “gasoline engines”, but I’m not convinced: since “they” is the subject of the second clause, it can generally refer back to the subject of the first clause on the GMAT without causing any trouble.
But we definitely have a modifier problem here: “fewer carbon dioxide” doesn’t make any sense, since “carbon dioxide” is a non-countable noun, and “fewer” can only be used with countable nouns. (If you’re not clear about that concept, try counting the noun out loud: “one carbon dioxide, two carbon dioxides, three carbon dioxides…” That makes no sense at all, right? So “carbon dioxide” is non-countable.)
(D) The first part of the underlined portion isn’t necessarily WRONG, but it definitely isn’t great: “gasoline engines that have a comparable size” is a really crappy way to say “gasoline engines of comparable size.” I just don’t think it makes sense to use the word “have” in this context, since gasoline engines don’t really possess size.
More importantly, we have a problem with the non-countable modifier “less”, since it seems to be modifying both “carbon dioxide gas” (non-countable) and “other gasses” (countable) – and “less” can’t modify a countable noun.
(E) The first part of the underlined portion suffers from the same problem as (D): “that have a comparable size” is a lousy way to say “of comparable size.” But again, I wouldn’t necessarily eliminate (E) based on that issue by itself.
The other problem is the same as in (D): “less” seems to modify “other gasses”, and that doesn’t work. Plus, I’m really not sold on the idea of using “having” to modify “gasses” at the end of the underlined portion – the version in (A) (“gasses that have…”) seems a little bit better.
比较的题型：1）比两样东西（名词），2）比两个动作（动词）。
这里比较的是两个动作，所以，有一个省略用法 [sub+verb]+modifier，只保留modifier，选C。
如果是比较两个东西, 比如circulation in.... is lower than that in ....，就应该是D。
（newspaper）{had} 《lower circulation》 in the six months than（newspaper）{ had} in a similar period
改写为两个东西比较：the circulation of newspaper in the six months is lower than that in a similar period
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A选项：在逻辑上，能在较小的树顶上出现的肯定是“花冠 （crown）”，而不可能是“树干（trunk）”（树干总不能长在树顶上）,更不可能是“花冠”和“树干”。(单词意思不懂！)另外，grow已经表达了“长大”的概念，不用再加介词up to，只需用to即可。