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

   Answer: ae

为什么选E？

capability后不是要跟OF吗？

A有什么不对？

用A可能会有歧义:不知道是说发明了a new type of jet engine最终可以***,还是说这个只是那些最终可以**的一种.

而E就避开了这个问题.

至于说capability没有说一定要加of

google的一句话:

Up to 30 new countries could have the capability to build a nuclear weapon, on top of the nine current nuclear powers, ElBaradei has warned. Photo: AFP/file

答案是 A   that跨前指代jet engine

E错：

1、"it could" run-on sectence

2、could和have the capability to     重复

3、have the capability to     表达不好

另外capability to do/capability of doing  都有

答案E中，could 與 have the capability to...語意重複

A正確

解释一下 that 跨前修饰 jet engine, 因为that引导的定从太长，如果按正常语序a new type of jet engine that could eventually propelaircraft anywhere in the world within .....or help ...permit is being tested. 这样的话句子就显得“头重脚轻“，所以为了使句子平衡，把that引导的定从放在了后面。