(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.)
for anybody who wants to know the answer, --- by Ron
probably the easiest way to go here is to remember this as an idiomatic usage of the construction "known to". if the action is in the present, then you use "known to VERB"; if the action is in the past, then you use "known to have VERBed". as far as i know, these are the only two possible forms.
"known as" is incorrect unless it is followed by a noun:
Albert Einstein made his living as a patent clerk, but he was far better known as the original proponent of the theory of relativity.
--> correct (note that "proponent" is a NOUN)
1) Pronouns - The opening of the sentence states that "In a blow to THOSE…."; here, the word "those" is a pronoun. In the answers, we see that some have an extra pronoun and some don't. Since we already have a pronoun, we do NOT need another pronoun immediately next to it. That extra pronoun is redundant (and unnecessary). Eliminate A, B and C.
开头句those后面不能跟代词，否则重复
2) Verbs - Between D and E, we have the verbs "enables" (present tense) and "will enable" (future tense). Since the watchdog group "recently uncovered the trick", we're dealing with something that's happening in the immediate present. The verb "enables" is required here. Eliminate E.
【recently uncovered a trick】已经发生，后面用【will enable】不妥
build 和 to build 差别都不大（感觉太细了），主要是后面是否跟一个非限定性定语从句which的区别：如果是选DE 就会变成 a bridge, which shows how their idea would work. 只有这座桥才能展示他们的idea
但实际上是他们做了a number of structures to show·····（我也翻船了，太讨厌这种要慢慢品的题目····
- an average is a single data point, so there's no such thing as 'averag[ing] from 1.8 to 6.3'. on the other hand, it's quite possible for a single data point to fall between two given values.
this sentence is about the AVERAGE global warming over a certain period. so, any sentence containing "from... to..." would be nonsense.
an average is a single value.
B) you can't use 'that' in this sort of construction, because constructions using 'that of' (or other preposition after 'that') must have EXACTLY parallel structures. in other words, if the second half says 'that during 10,000 years', then the preceding half must say 'the growth of ___ during something else' (or some other time preposition, such as before or after, in place of during).
there's nothing ungrammatical about 'from when', because the clause starting with 'when' is a perfectly legitimate noun clause (i.e., 'when agriculture began' serves as a noun. however:
- regardless of where the gmat stands on the issue, 'the beginning of agriculture' is unquestionably better than 'when agriculture began' (i.e., an actual noun is almost always superior to a circuitous noun clause, when possible)
C) first, you've got a "which" modifier that isn't preceded by a comma, so that's an automatic failure. (note that you can use preposition + which without a comma -- e.g., the box in which you placed your valuables -- but you cannot do so with just plain "which".)
more importantly, "had been" is not parallel to anything in the other half of the sentence; in order to use a parallel structure that contains a form of "to be", you must have another form of "to be" in the other half of the parallel structure.
D) you can't use the present perfect if the time interval is over. If the trend continues into the present day, then the present perfect is appropriate.
Even if that were fixed, choice D still suffers from fatal wordiness / lack of concision, especially in comparison to the correct choice."
E) 'what it did' doesn't make any sense:
* the growth didn't 'do' anything
* there's no other verb to which 'did' could logically be parallel to complete the comparison
1 * if you have than/as + subject + FORM OF "TO BE" as the second half of a comparison, then you must have another form of "to be" in the first half of the comparison.
or, there should be something in the first half that would make sense with "to be" in front of it.
2 * if you have than/as + subject + HELPING VERB as the second half of a comparison, you can have just about any other form of the same verb in the first part, as determined by context.
3 * if you have than/as + subject + FORM OF "TO DO" as the second half of a comparison, then you must have an ACTION VERB[/b] (or another form of "to do") in the first half of the comparison.
here are some examples:
#1
the air quality of las vegas is higher this year than it was in 2005.
parking spots are disappearing much more quickly today than they were yesterday.
#2
james can negotiate with salespeople more effectively than stephanie can. (comparing their abilities)
james can negotiate with salespeople more effectively than he does. (his ability exceeds his actual performance, probably because he just isn't trying very hard)
#3
parking spots disappeared much faster today than they did yesterday.
tanya eats more slowly than she did when she was a teenager. (note that "did" doesn't have to have the same tense as the action verb)
you can't say "jump at QUANTITY". here, "to" is correct.
on the other hand, if the word "at" is part of some other construction, such as a time marker, then it could appear:
consumer spending always jumps at the end of the year, when the holiday season arrives.
here, "jump at" isn't really a construction; it's just "jump", followed by "at the end of the year".
Much more importantly, "smaller" vs. "less of a" is there just to distract you. You don't actually need it to solve the problem.
* You can eliminate a/b/c because the comparison has two possible meanings: (1) commitment to work vs. commitment to family, or (2) young people's commitment to work vs. their parents' and grandparents' commitment to work.
* You can eliminate E because "than" is there without "less".
(a) is vague because it's overly indirect: the meaning of "investigate changes ... as to their effects" is unclear. what's more, it's probably considered unidiomatic as well, at least in this sort of context.
(b) = correct
the participle "investigating" follows "experiments" immediately. no filler words are necessary; this is good concision.
the wording is clear; there are no awkward double possessives, etc., as in some of the other choices.
"would" is used properly here, as a past-tense form of "will". (i.e., if this sentence were translated into the present tense, it would read "...that changes ... will have")
(c) is ridiculously wordy; there's no way you should give this choice any serious consideration. if you don't realize pretty quickly that this choice is wrong, you should go back and read through a bunch of correct OG answers, trying to internalize the sights and sounds (the "vibe") of the correct answers.
(d) "changes in working conditions' effects" is at best awkward and vague, and at worst ambiguous: the intended meaning is the effects of the changes, but this sentence seems to indicated the effects of the conditions themselves. in other words, a literal reading of this sentence seems to indicate that the conditions themselves haven't changed - only their effects have. that's not the intended meaning of the original.
(e) "what the effects" is ungrammatical.
also, in constructions of this sort, "what" is generally redundant / unnecessary; it's better merely to say "to investigate X" rather than to say "to investigate what X is" (or other such wordy construction).
if a sentence contains a COMPOUND NOUN (X and Y), you CANNOT use a pronoun to refer to just X or just Y, unless you use "the former" or "the latter" to make the distinction explicit.
in (d), it's technically incorrect to use "they" because there is no place in which both systems are mentioned at once (e.g., with "and").
idiom: there were no X's or Y's.
(A) were no Jane Austens or Brontë sisters ("were" works with both items because they're both plural)
(C) was not Jane Austen nor the Brontë sisters (singular "was" doesn't work with plural "sisters")
We can eliminate options C, D, & E because they use a singular verb with the plural Brontë sisters.
There were no Xs or Ys = CORRECT
There were not Xs or Ys = INCORRECT
A one-million-year-old skull主语； bearing traits定语，修饰skull，携带着特征 ；associated both with Homo erectus and Homo sapiens 定语，修饰traits，特征是有关H
真正的谓语动词是has been found
indicating伴随状语
"until healing" would apply to the subject "swelling and stiffness". those don't heal; the injured area does. therefore, you need a construction that changes the subject to "the injured area" -- or a pronoun that stands for those words, as in the actual correct answer.
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显然地，和“个人电脑工业持续强劲”对比的，是分析师预言的内容，而不是分析师们做出预言这个行为