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".

E = clear winner, B = clear loser.

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'.)

PAST TENSE vs. PRESENT PERFECT TENSE

--

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.)

BCE与原文信息直接相反；
D 中雨的降雨总量（注意是全年总量！不是单次的），1990是1910的两倍。假设，1990的单次降雨都是2 inches，1910的单次降雨都是1 inches，只有在1990的中雨天数 大于或等于 1910的中雨天数时成立。然而1990的降中雨天数一定是小于1910的，所以一定不成立。
A：次数少，但是每场都是大暴雨

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.)

well, d has two problems, at least:
- 'projects X to do Y' is unidiomatic. (you can just say 'projects NOUN', as is done in choice e, or you can say something like 'projects that X will do Y').
- 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.

i've seen 'of between' in this sense before - think of the phrase 'between 1.8 and 6.3' as standing for a single number, and parse the sentence accordingly (it reads as if it said 'average g.w. of 5 degrees', for instance) - so, if the original poster has copied the problem correctly, we now know that the gmat accepts that construction.

Prep2007E1-SC-154

In general,

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)

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

比较前后状态一致

把主谓抽出来jay can remember and tends to

the fused clavicles (the "wishbone") of birds differ from the unfused clavicles of theropods.-->鸟类的锁骨是fused而theropod的是unfused（这是两种不同样的骨头），所以认为鸟类不是从theropod进化来的
B中的内容是作者提出的，科学家对于lung这一点只是提出质疑lung并没有说evidence的事情

第一过完必须要谨慎，第二突然出现的代词要找到先行词

第三題: Ad revenue (in $) per dollar charged for advertising impressions
CPM=1(per dollar charged)=Ad Revenue / (Readership * Pages)
因此Ad Revenue=Readership * Pages，找Readership*Pages最大(即revenue最大)