天山4-30

Unlike the short flights of the shuttle and earlier spacecraft, which carried sufficient power in fuel cells and batteries, a permanently orbiting space station will have to generate its own electricity.

A.      the short flights of the shuttle and earlier spacecraft, which carried sufficient power in fuel cells and batteries

B.       the shuttle and earlier spacecraft, with sufficient enough power in fuel cells and batteries for their short flights

C.      the short flights of the shuttle and earlier spacecraft, which enabled them to carry sufficient enough power in fuel cells and batteries

D.      the shuttle and earlier spacecraft, which were capable of carrying sufficient power in fuel cells and batteries for their short flights

E.       the flights of the shuttle and earlier spacecraft, whose shortness allowed them to carry sufficient power in fuel cells and batteries

answer：D, no clue at all

用排除法：

unlike a, b... a, b 對稱。
b= space station
a= shuttle and sapcecraft可以
a=flights 錯 排出  a e

sufficient 與 enough 語義重復 排除

所以只有D是對的
再分析下D,不像航天飛機和早期的宇宙飛船一樣，他們都能夠自行攜帶足夠的能量，而空間站是自己產生電。符合平行對稱。

unlike A, B do

AB要是同一类的词

ACE错，后半句讲的是永恒的空间站会自己发电。前半句应该对应航天飞机带足够的燃料，而这里的A是short flight，B是a permanently orbiting space station ，不对称

BD中，the shuttle and earlier spacecraft对应a permanently orbiting space station ,

而B答案中sufficient enough重复了，所以正确答案是D