[原创]黄皮语法OG11-103

The development of a new jumbo rocket that is expected to carry the United States into its next phase of space exploration will be able to deliver a heavier load of instruments into orbit than the space shuttle and at a lower cost.

D. A newly develped jumbo rocket,which is expected to carry the United States into its next phase of space exploration,will be able to deliver a heavier load of instruments into orbit than the space shutttle can,and at a lower cost.

E. A newly edveloped jumbo rocket,which is expected to carry the United States into its next phase of space exploration,will be able to deliver a heavier load of instruments into orbit than the space shutttle and to cost less.

答案是D

我不懂and at a lower cost中的and连接前面哪一部分，做什么句子成分。

E答案如果加上can的话我认为也对，是不是？而且我觉得to cost less可以和to deliver并列，但答案说不可以。为什么?

答案是

will be able to deliver...., and (will be) at a lower cost.

谢谢connie4895

偶懂了~~

我不同意这种并列的说法，我认为是：

 will be able to deliver a heavier load of instruments into orbit than the space shuttle can, and (deliver a heavier load of instruments into orbit )at a lower cost(than the space shuttle can)

请指教！

请问这个助动词为什么是补can?补do对不对？