GWD 13-6

今天作第一套gwd，一塌糊涂，v错了15个。都不知道自己是怎么搞的。

Q6:

After more than four decades of research and development, a new type of jet engine is being tested that could eventually propel aircraft anywhere in the world within two hours or help boost cargoes into space at significantly lower costs than current methods permit.

A.       tested that could eventually propel aircraft anywhere in the world within two hours or help

B.       tested that could eventually have the capability of propelling aircraft anywhere in the world within two hours or to help

C.       tested, eventually able to propel aircraft anywhere in the world within two hours, or helping

D.       tested, and it eventually could propel aircraft anywhere in the world within two hours or helping

E.        tested, and it could eventually have the capability to propel aircraft anywhere in the world within two hours or help

这个题目看不明白，也看了讨论，我选的A，但是觉得A和E都有点问题，A中的that指代看不清楚。而且我记得，that是不能单独指代前面的名词作句子主语的一样（记不清楚了，NN指点）还有就是E选项，如果help和propel 和have 都并列。怎么回事？

请见： 【讨论连接】GMAT语法讨论汇总  [ 2 3 4 5]

BTW，这道题是有争议的。