请教og10-177

OG对于D的解释是，合理的语法为X is the reason why Y，而不能说X is why Y。

我记得"it is why..."，还有"this is why..."是一个很常用的基本英语表达啊，自己写作文还有口语的时候都常用。难道是错的吗？

177. So poorly educated and trained are many young recruits to the United States work force that many business executives fear this country will lose its economic preeminence.

(A)  So poorly educated and trained are many young recruits to the United States work force that

(B)  As poorly educated and trained as many young recruits to the United States work force are,

(C)  Because of many young recruits to the
                United States work force who are so poorly educated and trained,

(D)  That many young recruits to the United
                            States work force are so poorly educated
                and trained is why

(E)  Many young recruits to the United States
                work force who are so poorly educated and
                trained explains why

A, the best choice, uses the idiomatic form So X that Y to establish a cause/effect relationship between clauses X and Y. In B, the subject of the as ... as clause (young recruits) should be the subject of the main clause as well (e.g., they). Furthermore, main clauses following concessive clauses must express a contrasting notion: for example, "As ill-prepared as they are, they nevertheless find good jobs." C offers a wordy, convoluted because clause. In D, the sentence form X is why is unidiomatic (X is the reason why would be idiomatic but needlessly wordy and awkward). E exhibits subject-verb disagreement: young recruits ... explains why.

谢谢你哦