og 242

问d为什么不对呢？

242. Even their most ardent champions concede that no less than a technical or scientific breakthrough is necessary before solar cells can meet the goal of providing one percent of the nation's energy needs.

(A)  that no less than a technical or scientific breakthrough is necessary

(B)  that nothing other than a technical or scientific breakthrough is needed

(C)  that a technical or scientific breakthrough is necessary

(D)  the necessity for an occurrence of a technical or scientific breakthrough

(E)   the necessity for a technical or scientific breakthrough occurring

the answer is C

我觉得D有些wordy,还有些模糊

the necessity for an occurrence of a technical or ( of a) scientific breakthrough

别的也说不上来。