Although fullerenes--spherical molecules made entirely of carbon--were first found in the laboratory, they have since been found in nature, formed in fissures of the rare mineral shungite. Since laboratory synthesis of fullerenes requires distinctive conditions of temperature and pressure, this discovery should give geologists a test case for evaluating hypotheses about the state of the Earth's crust at the time these naturally occurring fullerenes were formed.
Which of the following, if true, most seriously undermines the argument?
(A) Confirming that the shungite genuinely contained fullerenes took careful experimentation.
(B) Some fullerenes have also been found on the remains of a small meteorite that collided with a spacecraft.
(C) The mineral shungite itself contains large amounts of carbon, from which the fullerenes apparently formed.
(D) The naturally occurring fullerenes are arranged in a previously unknown crystalline structure.
(E) Shungite itself is formed only under distinctive conditions.
Tricky one. I agree B is tempting, but I think I'd go with D here.
Fullerenes found in lab first. (Does it really say "found"? Not created or something like that?) Then were found in nature. The lab fullerenes were synthesized at specific T and P. Therefore, geologists should be able to tell something about T and P of Earth's crust when natural ones were formed.
Connection is the assumption that the way the fullerenes were formed in the lab is analogous to the way they were formed in nature.
I'd label choice B "slightly weakens" - it opens up the possibility that maybe the fullerenes found on Earth came from outer space. Doesn't mean they definitely did, though.
Then I get to D and realize it's better than B - it strongly undermines. The naturally occurring Earth fullerenes are definitely of a different structure than the lab-made ones. If that's the case, then I can't just assume that the process to make them in the lab is analogous to the process to make them naturally.作者: littlecloud 时间: 2010-2-5 14:08
谢谢Prayer，而且确实B中的some不够有力。BTW, 我回忆起很多年以前的化学课，金刚石和石墨都是碳构成的，呵呵。。