The number of plant and animal species

[RonPurewal]

as for choice D:

• yes, the use of two "that"s in such close proximity is ... ugly. "ugly" is not an error, though-- it will NEVER be the only issue.

• the sentence is constructed in a way that doesn't make sense.

analogy:
The only animals that live in the Arctic that can also survive in the Sahara are xxxx and yyyy.
(again, this sentence is awkward/ugly, but that's not the point right now.)
this sentence is parsed as follows:
The only ((animals that live in the Arctic) that can also survive in the Sahara) are xxxx and yyyy.

try that with choice D and you'll see what's wrong.

[douyang]

as for choice D:

• yes, the use of two "that"s in such close proximity is ... ugly. "ugly" is not an error, though-- it will NEVER be the only issue.

• the sentence is constructed in a way that doesn't make sense.

analogy:
The only animals that live in the Arctic that can also survive in the Sahara are xxxx and yyyy.
(again, this sentence is awkward/ugly, but that's not the point right now.)
this sentence is parsed as follows:
The only ((animals that live in the Arctic) that can also survive in the Sahara) are xxxx and yyyy.

try that with choice D and you'll see what's wrong.

Hi Ron, although I see the sentence could better constructed if we put an "and" between "Arctic" and "that", I actually don't see why the analogy sentence is constructed in a way that does not make sense. More specifically, I don't understand the coloring above. Can you elaborate it a little more? Thanks.

[RakshithG27]

'to become extinct' does seem, to my eyes, more awkward and wordy than 'to extinction', but there are other issues in choices b and c.

choice b:
biggest problem = incorrect idiom: 'known as having forced'
known as is used with nouns: al capone was known as a gangster rather than as a tax cheat, but he was ultimately imprisoned only on charges of tax evasion.

with verbs, you have to use 'known to infinitive' or 'known for gerund'.

choice c:
fatal change of meaning.
this sentence implies that we are currently 'forcing [these species] to become extinct', a meaning that not only differs from the original but also borders on absurdity.
the original meaning, which we're not allowed to change, is that humans have forced the species into extinction at some point in the last 500 years, not that humans are doing so currently.
analogies:
the island's natives are known for stealing tourists' money, passports, and jewelry. --> these things go on today
the island's natives are known to have stolen tourists' money, passports, and jewelry. --> not necessarily still happening, but it has happened at some point

hope that makes sense.

Ron,

I have read many times that we cannot use 'Preposition+Noun+Gerund' or 'Preposition+Gerund' and that we can only use 'Preposition+Noun'.

How is that we can use 'For+Gerund'? As 'For' is a preposition. Is this case an exception to the first rule?

Learning GMAT English is as learning a new language for me.

Thanks in advance.