The survival of coral colonies, which are composed of

Question

The survival of coral colonies, which are composed of innumerable tiny polyps living in a symbiotic relationship with brilliantly colored algae,  are being threatened, experts say, not only by pollutants like  agriculture runoff, oil slicks, and trash but also by dropped anchors, probing divers, and global warming.
A) are being threatened, experts say, not only by pollutants like
B) are being threatened, experts say, by not only pollutants such as
C) is not only being threatened, experts say, by pollutants such as 
D) is not only being threatened, experts say, by pollutants like
E) is being threatened, experts say, not only by pollutants such as

please underline

terp26 · Answer

E, is agrees with survival, not only X but also Y, X and Y need to be parallel

giantSwan · Answer

hmmm,

I understand why "is" is correct.
I understand why "such as" is correct.

I'm having trouble with the parallelism...huntgmat, do you mind providing a little more?

ashkrs · Answer

let me try ..huntgmat sorry if i am hijacking this...

not only X but also Y is correct idiom. And for idiom to be correct X and Y must be parallel. Means if X is noun , Y should also be a noun. If X is a verb then Y should also be a verb and follow same tense.

Since you have understood is and such as , so its between C and E.
take a look at C
is not only  being threatened , experts say, by pollutants such as.....but also  by droppped pollutants

they are not parallel. X is verb and Y is noun.

E is precise.Both X and Y are nouns.

huntgmat · Answer

Thanks ashkrs,

Just to add.

If you wanted to make C correct , you will need a contruction something like

is  not only   being threatened , experts say, by pollutants such as..... but also  being threatened  by droppped pollutants ....

Since we take out "being threatened" outside of not only .... but also .... , the construct should be parallel
with what are you threatened with.

giantSwan · Answer

Thanks -- you guys are great. It's making studying for this test MUCH more managable/painless.

giantSwan · Answer

Also,

Do either of you have a method for studying idioms?

Or did you just embark on "rote learning" memorizing all of them?

- gS

huntgmat · Answer

I am never good in memorizing.... :crying In my notes i note the question when i get a different idiom type question & keep on revising the usage with the examples. That's all i do.....

The survival of coral colonies, which are composed of

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