D if recognized and applied, students 句中主语是学生 语义是如果被学生被认知和使用 不符合逻辑。注意看啊！因为if后面是一个完整的句子和前面句子的主语是不一样的不能公用下来！！

D平行不正确

After the islands separated, the isolated lizard populations would have become distinct species while also retaining their ancestors' niche adaptations.

我理解B是省略，但不省略的话，应该是什么呢？a greater proportion than that was？

D 取非之后说的是 会惩罚第一次没有做好（导致 later had to be reworked）的工人。如果是这样的话，工人应该第一次就更加认真做（应该不想被罚款），那么第一次的满意度更好才对！但是这样想就质疑前提了，因为文章结论的Premise是“When initial repairs are inadequate”。总的来说D 和我们想要削弱这个原因（工作复杂需要二次返工）没关系。

A选项师生比例高是削弱，且A选项用过去的信息未必能类比到将来

错因：读B选项读的太快了，没有get到B选项正确的意思

认真审题！错因：题目问的是resource-based theory 的proponents，而不是第一段中的Proponents of IT。

a is correct because it's the only choice combining proper parallelism with correct grammar. the cause is not so much that x as that y.
b: previous poster is correct about 'their', but a much more obvious problem is bad parallelism. the cause is not so much their x as that y.
c: lots of things
- 'it is not so much the cause...' seems to say that the phenomenon mentioned doesn't really cause the mentioned effect
- you don't use 'much' twice; the proper construction is 'not so much ... as'
d: mostly the same things that are wrong with c, plus even more (go ahead and reply if you don't see anything wrong with d)
e: a couple of things
- as in choice c, 'it is not so much the cause of genetic irregularities' seems to say that the phenomenon mentioned isn't the cause of the given effect
- 'breeds of dog to be bred for looks' seems to imply dogs meant to be bred for looks (analogy: on the table are the five packages to be shipped)

it's one of the worst official problems i've seen ... but we have to learn from it

(a)
* poor parallelism. (a correct gmat choice would almost always include much closer parallelism, such as ...they do blah blah blah, like exercise, and they do blah blah blah, like morphine)
* can't use 'these' as a standalone pronoun. (this/that/these/those are only acceptable as adjectives - these people, that hypothesis, etc. - or as part of parallel constructions - the symphonies of beethoven vs. those of bach, etc.)

(b)
faulty comparison (a pain-relieving effect is compared directly to morphine, rather than to the pain-relieving effect of morphine as obviously intended)

比较对象是speeds；
B时态错，要用将来时与than后面的现在时区分；且用定语从句修饰speed没有E选项简洁

B中，即使现存的不是small volume，比如与去年相同，仍能得到结论，所以这里构不成assumption。即否定之后并不能完全否定结论。

first, examine the split between 'more ergonomic' and just 'ergonomic'. in this case, we must preserve the meaning of the original statement: the new design is more ergonomic than the old design. if we change this to just 'ergonomic', we're attaching an implication that the old design simply wasn't ergonomic (and that the new design, by contrast, is) - an unacceptable implication. that gets rid of answer choices c, d, and e right there.

another item to examine is parallelism. in this case, in the construction 'X rather than Y' (or its analogues, 'X and not Y' and 'more X than Y'), items X and Y must be parallel.
choice a: conforming... rather than flaunting... <-- good parallelism!
choice b: to the body's shape and not to flaunting shape <-- logically nonparallel and also awkward
choice c: can't use 'more' together with 'and not to' (these are exclusive constructions, sort of like 'both' and 'as well as': if you use one, then you can't use the other), so we don't need to consider the parallelism in the first place.
choice d: can't use 'more' together with 'rather than'; also, bad parallelism between to the body's shape and shape flaunted...
choice e: more to the shape... than flaunting... <-- nonparallel

in fact, the winning choice (a) is the ONLY choice that properly compares 'conforming' and 'flaunting' in parallel. all of the other constructions also change the meaning of the sentence via their alterations of the words.

choice e：Let's compare C to the correct answer D.

C. come from antioxidants"”compounds also found in beta carotene, vitamin E, and vitamin C, and
D. come from antioxidants"”compounds that are also found in beta carotene, vitamin E, and vitamin C and that

Since the word "and" is a parallel marker, we must check parallelism. Notice how D is parallel after the dash:
compounds that are . . . . and that inhibit
We have nice verb parallelism here.

C breaks this parallelism by joining a noun and a verb:
compounds . . . and inhibit

Choice e：
yes, something is indeed wrong.

at best, 'they' is an ambiguous pronoun that potentially refers either to 'antioxidants'/'compounds' or to 'health benefits'. at worst it refers to 'health benefits', the subject of the preceding sentence, by default. either way, you've got problems.

the other problem is that a single dash of the sort that sets off the descriptor in this problem is akin to a single comma: both set off an appositive phrase, which is NOT allowed to contain independent clauses (such as the one beginning with 'they' in choice e). choice d follows the rules here, as, after the dash, it contains only subordinate clauses.

if you use a single dash, then the stuff that is set off by the dash must actually continue all the way to the end of the sentence. if you are going to block off a modifier with dashes, then you must use two dashes to block off the modifier.

i.e., there is no such thing as a modifier that is blocked off by a dash on the left, but by a comma on the right. if you have a modifier that does not extend to the end of the sentence, then you must use either two dashes or two commas to set it off.

No longer do many cities in United States have a river as the focal point of urban life
... is grammatically equivalent to ...
Many cities in United States no longer have a river as the focal point of urban life

also
Only yesterday were we told about the layoffs
... is equivalent to ...
We were told about the layoffs only yesterday

the primary difference between the examples in each pair is rhetorical. in particular, the first one in each pair -- the one that places the adverb (only yesterday, no longer) in front -- would be written that way in order to emphasize the meaning of that adverb. from the standpoint of grammar, there is essentially no difference.

the correct answer here is still pretty ugly, so let's criticize the four incorrect choices.

choice a:
faulty comparison:
'unlike many u.s. cities, ... the river in san antonio...' --> can't compare cities to a river

choice b:
comparison isn't so good:
the second part should start directly with 'the river' (instead of 'in san antonio the river...'), so that the comparison is more clear.
much more importantly, poor use of the relative pronoun 'which':
'...cities in the united states, which is no longer the focal point...'
relative pronouns like which, by default, refer to the noun that's closest to the left, which in this case is the united states. therefore, this relative pronoun is used in a way that's either ambiguous (if you allow it to potentially refer to other nouns) or just plain wrong (if you follow the rule strictly).

choice c:
faulty comparison again
'the river...' is being compared to san antonio.

choice d:
drastic change in meaning
this sentence has completely gotten rid of any reference to the concept of 'no longer'. while all the other sentences say that things have changed, this sentence presents the situation as if it's always been that way.

"instead of" is generally restricted to nouns.

"rather than" can be used for essentially any part of speech at all.

they moved stiffly rather than gracefully (adverbs)
they moved to the left rather than to the right (prepositional phrases)
the car was red rather than blue (adjectives)
i bought a car rather than a truck (nouns) <–– this is the only sentence here that would work with 'instead of'
he chose to leave rather than continue arguing (infinitives)

Either "using" or "by using" would be fine.

Note that "using" is more flexible than other __ing words.
In fact, it's best to think of "using" as belonging to two different categories of words:
1/ It's an __ing word (= it can be used like other __ing words);
2/ It's a preposition, with a meaning largely similar to that of "with".
This is usage #2.

By the way, this distinction is immaterial here, because choice C (= the only choice with "by using") contains blatant non-parallelism.

Takeaways:
— Parallelism is the #1 error in SC. DO NOT think about other things before thinking about parallelism!
— If you're thinking about a small, nit-picky issue, STOP and ask yourself, "Am I being distracted from a larger issue?"
Here, "using"/"by using" is a distraction meant to take your eyes off of the parallelism. Looks like they got you.

SUBJECT + ACTIVE VERB + BY + NOUN is generally incorrect.**
SUBJECT + ACTIVE VERB + BY + VERBing is generally correct, if "VERBing" is the method or process by which the ACTIVE VERB is carried out.
e.g.
i prepared for the test by studying flash cards --> CORRECT
i prepared for the test by the study of flash cards --> INCORRECT

on the other hand,
SUBJECT + PASSIVE VERB + BY + NOUN is an absolutely fundamental form, if the NOUN is the thing/person that did the action to the SUBJECT.
e.g.
james was seen by two witnesses. --> CORRECT
--
** the only exceptions to this occur in the case of special idiomatic expressions. for instance, "by candlelight" is a known idiomatic expression, so constructions such as "i studied by candlelight" are correct.