The number of plant and animal species

[ankurbansal84]

The OA is A, but I marked E

3.The number of plant and animal species that humans are known to have forced to extinction in the last half millennium is over
a. Same
b. Humans are known as having forced to become extinct
c. Humans are known for forcing to become extinct
d. Are known that humans forced to become extinct
e. Are known as having been forced to extinction by humans

[agha79]

please underline the question

[ankurbansal84]

The number of plant and animal species that humans are known to have forced to extinction in the last half millennium is over
a. Same
b. Humans are known as having forced to become extinct
c. Humans are known for forcing to become extinct
d. Are known that humans forced to become extinct
e. Are known as having been forced to extinction by humans

[agha79]

Thank you for underlining the original question. This is an idiom question and if you catch that right away only choice "A" has the correct idiom.
"Known to" is correct idiom

[RonPurewal]

this is pure idiom.

it's not a faulty question, but it doesn't look like it's actually from an official source. what is the source of this question?

i also note that there's a problem number in front of it. if this problem were from the GMATPREP software (as REQUIRED in this folder), you'd have had to type it out, so the "3." wouldn't be there.

what's the real source of this problem?

[redable]

The number of plant and animal species that humans are known to have forced to extinction in the last half millennium is over 800.

(A) humans are known to have forced to extinction
(B) humans are known as having forced to become extinct
(C) humans are known for forcing to become extinct
(D) are known that humans forced to become extinct
(E) are known as having been forced to extinction by humans

I believe the question mentioned above should be complete.

a couple of questions:
1. the difference among are known to, are known as and are known for?

2. what's the role of "that" in this sentence?(not in the underline part)

3. "become extinct" is purely redundant or has different meaning from "extinction"?

Thank you in advance :)

[RonPurewal]

1. the difference among are known to, are known as and are known for?

"known as" is incorrect unless it is followed by a noun:
Albert Einstein made his living as a patent clerk, but he was far better known as the original proponent of the theory of relativity.
--> correct (note that "proponent" is a NOUN)

--

known for VERBing and known to VERB are both correct idioms, but they have different meanings.

known TO just means that, basically, it's a fact that so-and-so did/does such-and-such (i.e., we know this). in particular, this idiom does not impart any importance to this knowledge, nor does it suggest that the subject's primary reputation or fame results this action; it basically just states that X did/does Y.
* James is known to drink at parties --> this just means that it's an established fact that james drinks at parties; however, this does not suggest that james actually has a reputation as a big drinker. it basically just means "fact: the amount of alcohol that james drinks at parties is not zero."

known FOR, on the other hand, suggests not only that the mentioned action is a known fact, but also that it provides the principal basis for the subject's reputation, renown, or fame.
* James is known for drinking at parties --> this means that james has acquired a significant reputation for the quantity or intensity of his drinking at parties.

--

thus, while the idiom in choice (c) of this problem is grammatically correct, it's absurd -- this is not the primary feat for which humans are historically renowned.
(b) is actually unidiomatic, since "having forced" is not a noun.

2. what's the role of "that" in this sentence?(not in the underline part)

it indicates that the following noun is the direct object of the verb.
simpler example:
this is the food that i bought --> signals that the food is the direct object of "bought".
see also here:
post20511.html#p20511

by the way, this is totally one of those constructions that is a pain to break down formally, but will absolutely be second nature once you have seen it more than a few times.

3. "become extinct" is purely redundant or has different meaning from "extinction"?

i don't think that's a meaningful difference; i think that difference is there to distract you from the differences that are actually significant.

[redable]

Thanks your complete explanation :)

[RonPurewal]

Thanks your complete explanation :)

glad you found it helpful.