2 idiom errors in (b):
* "interact" MUST be paired with "with". "interact between" and "interact among" are unidiomatic.
* "among each other" is unidiomatic (as is "between each other"); you should write "among themselves" or "between themselves". but, again, this doesn't work with "interact" anyway, so the issue is moot here.
Answer A suggests that the manufacturers are making small cars efficient, i.e. they're changing small cars, but in fact they're making small cars that are efficient.
I don't think that pronoun ambiguity is the criterion here.
the sentence is supposed to say that today's small cars are more fuel-efficient than previous small cars -- i.e., OTHER small cars.
this is important, because you can't use a "they"/"their" construction (which would illogically imply that you're talking about the same small cars mentioned in the first part of the sentence).
the use of "those" in (c), on the other hand, accomplishes this distinction nicely.
analogy:
sprinters in texas can run faster than they can in north dakota.
--> illogical; in this sentence, "they" would be taken to mean "sprinters in texas" (i.e., not just sprinters).
sprinters in texas can run faster than those in north dakota.
--> makes sense; "those" = sprinters, in this case.
same thing with "they/their" vs. "those" in these instances.
In general, the point of "that" and "those" is to stand for nouns without any attached modifiers/descriptions.
There's an explicit contrast with "it" and "they", which stand for a noun with all of the attached modifiers.
E.g.,
The government of Country X is more stable than it was two years ago.
"It" = "the government of country X"
It is impossible to use "it" to stand for government in general. In this context, "it" can refer only to the government of country X.
Vs.
The government of Country X is more stable than that of Country Y.
"That" = "the government". NOT the government of country X.
The whole point of comparisons, of course, is to compare two different things. So, these pronouns are extremely useful because they're designed to do exactly that-- to stand for only the parts that are actually the same.
establishing the intended meaning is ALWAYS the FIRST STEP of ANY sentence correction problem!
without the intended meaning, most splits are actually impossible to decide, since the vast majority of grammar rules just serve to specify the meaning of whatever construction.
B and D - Incorrect because they do not include the "he" in the end. Without this subject, the rest of the sentence doesn't make much sense.
C - Incorrect because the primary clause is just a fragment:
* Remove the parenthetical phrases "even though...telescope", and "in 1609" and you will see that C is missing a verb as it reads: "Gallileo on hearing that such an optical instrument had been made, he quickly built his own"
E - Incorrect because of the double negative "Even though...but when he heard". Double negatives are a no-no on the test.
C, D, and E - Incorrect because "even though" is not appropriate in this case as it isn't consistent with the intended meaning of the sentence. "Even though" should be used to show mitigating circumstances, or to introduce a paradox as in the examples below:
it's an adverbial modifier that modifies the action of the clause with which it's associated. technically, that action is encapsulated by "is (able)", although it's probably easier to think of it as "modifying the entire clause".
with modifiers that serve as adjectives (such as "..., which ..."), it's crucial that you isolate the single noun modified by the modifier.
on the other hand, with adverbial modifiers, it's unimportant to isolate the single word being modified, because the placement of the modifier isn't restricted anywhere near as severely as with adjective-type modifiers.
as stated above, "dependent" is an adjective, modifies the tree. "depending" is a participle (which introduces an adverbial modifier that modifies the action of the clause, rather than modifying a noun).
the problem lies in the different meanings of the 2 words. "dependent" refers to reliance on another for some kind of support (as in "my children are dependent on me for their food and shelter"). so not only is that choice sketchy in terms of grammar, but its meaning is also all kinds of wrong: it makes no sense to say that a tree is "dependent" on its size (does its size provide it with food or water? etc)
when you see this sort of thing tested, this is all you generally need to do:
* find the second part of the comparison (after the signal)
* figure out what the first thing should be (to create parallelism)
* see if it's there
E:
the second thing (after 'as') is for her skillful wax renderings of popular public figures.
for + THING
...so the first thing should be for her eccentric personality.
this exact construction is there.
B:
the second thing (after 'as') is for skillful wax renderings of popular public figures.
for + THING
...so the first thing should be for her eccentric personality.
this isn't there. instead we have "for + verbING".
Ron：
choice a: bad parallelism
because of... is not parallel to for...
choice b exhibits poor parallelism:
having an eccentric personality is placed in parallel with skilful wax renderings....
choice c: extremely bad parallelism
- one part is a phrase (because of ...), and the other part is a complete clause (she was for her ...)
- same issue as choice a, because vs. for
choice d: bad parallelism
- you can't get rid of the 'for' in the second part (it should be '...as for having...')
- wordy (compare with the compact wording in choice e)
choice e exhibits proper parallelism, in that both of the parallel items are noun phrases (the principal nouns being personality and renderings).
there are two splits you should use to narrow down this problem:
(1) the second half of the construction 'ten times as much ... ____' is as, not than. therefore, you can eliminate answers (a) and (e), which contain 'than'. (i'm assuming that (e) is supposed to say 'than', not 'then'; i don't think the gmat problems would that blatant an error)
(2) the pronoun 'it' is inappropriate, because 'it' must refer to the ENTIRETY of the noun phrase serving as an antecedent.
for instance, the following is an improper sentence: last year's attendance was ten thousand greater than it was this year
in the above sentence, the pronoun 'it' must necessarily refer to last year's attendance, not just attendance.
the problem in this post has the same issue: the pronoun 'it' must refer to more than ten times as much energy, not just energy - an interpretation that makes no logical sense. therefore, all answer choices containing the pronoun 'it' are wrong.
if you don't like '...than was the case', you should learn to like it; this is one of those phrases that the gmat writers use to refer to concepts that don't fit under the usage constraints of traditional pronouns. (another popular one of these constructions is 'do so'.)
The PAST tense is used for:
* HISTORICAL ACTIONS
Ex: Mexico achieved independence in 1810.
* POINT ACTIONS that do not have a direct bearing on the current situation
Ex: Thomas, who is the president of First National Bank, won two Olympic medals in track
and field.
* ENDURING ACTIONS/STATES that are FINISHED
Andrea was the president of First National Bank from 1990 to 1994.
--
The PRESENT PERFECT is used for:
* POINT ACTIONS that DO have a direct bearing on the current situation
EX: Thomas, who is the fastest sprinter in his country’s history, has won two Olympic medals
in track and field.
* ENDURING ACTIONS/STATES that are STILL ONGOING
Carlos has been the president of First National Bank since 2001.
Note that, in some cases, the same point action could be described either by the past tense or by the present perfect tense!
(See the two examples with "Thomas" above.)
When a sentence opens with "In xxxx", followed by a comma, that modifier describes the entire action of the sentence.
In my house, children wear respectable clothes.
--> This is a general statement about the dress code at my house: If children are there, they dress respectably.
It's not a statement about any child(ren) that are actually at my house right now.
If "in xxxx" follows a noun, without a comma, then it describes the noun.
The children in my house wear respectable clothes.
--> There are children in my house right now; this sentence describes their sartorial habits. (This sentence implies nothing about what generally happens in my house.)
Answer choice A puts the events in proper perspective:
* The comet disintegrated last year; this was a one-time event.
* It provided new insights. Since it was a one-time event, it's appropriate to say 'provided' (simple past tense), unless the same event has CONTINUOUSLY provided newer and newer insights, in which case 'has provided new insights' would be better. But there's no indication of the latter in this sentence.
* The 'forcing' is a possible future event.
According to choice E:
* The comet's disintegration produced new insights last year.
And, more absurdly,
* The disintegration produced those insights in full view of ground- and space-based telescopes!
from this example, you can learn that 'as well as' is not strictly a parallel marker.incidentally, in the official correct sentences, i've never seen 'as well as' followed by anything other than a noun. (remember that '__ing' can be a noun; that's the role played by 'emitting' here.)
i wouldn't elevate this to the status of a 'rule', since as well as is also widely used to connect other things, such as adjectives (His review was insightful as well as thorough).
on the other hand, i am comfortable positing these two things:
• don't follow 'as well as' with a verb
• be suspicious of any choice in which 'as well as' is followed by something other than a noun. (if you can't see any other reason to eliminate, use this as a guessing method.)
i do believe that we've seen examples in which relative pronouns stand for the entire phrase 'X of Y' rather than just the Y immediately preceding the comma, but that situation is rare indeed and should be avoided unless absolutely necessary (= it happens in all the choices, so you can't get away from it).
in this case, then, choice e, which avoids this whole relative-pronoun mess, is certainly preferable to choice d, which doesn't.
still, you can rule out choice d for other reasons:
* 'seemed to be using': unacceptable change of meaning. the past-tense 'seemed' says that that's the way it seemed to the mayans living in cancun long ago, whereas the sentence is clearly designed to say that's the way it seems to us now.
* i don't like 'in becoming', which smacks of what the gmat would call 'idiom error'. there's no answer key for these things, of course, but i do have the feeling that the gmat would label this as an idiom error.
Though it is not a definitive grammatical principle, sentences with infinitive forms are often less awkward and wordy than those with the -ing (progressive forms). In this particular case, not only is "looking at" in choice E nonsensical, as to look at implies visual skills rather than logical considerations, but also the verbs using and attract are not parallel. Answer choice C, the credited response, correctly employs the parallel verbs improve and attract.
well, strictly speaking, a waterfront is not a way of doing something; it's a physical frontage that is just sitting there next to the water. So, literally, that statement is nonsense.
More importantly, if you compare that choice against choice (C), you should notice that (C) is more concise and better worded.
(That's the way you should make all decisions about "wordiness""”they should be relative decisions, not absolute decisions.)
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2 idiom errors in (b):
* "interact" MUST be paired with "with". "interact between" and "interact among" are unidiomatic.
* "among each other" is unidiomatic (as is "between each other"); you should write "among themselves" or "between themselves". but, again, this doesn't work with "interact" anyway, so the issue is moot here.