白勇第十章P302第6题

实在找不到是否有人讨论过，就敲上来吧~~暴长的题简略写，见谅

A rocket, which..., will be able to deliver a heavier load of instruments into orbit than the space shuttle can, and at a lower cost.

这是正确答案，我对can的补出有疑问。请问可以补出一个不一样的情态动词么？

另外，最后and+介词短语我也不清楚这是什么用法，有人可以解释一下，或者从其它练习里举个例子么？BY上说是修饰deliver的。

be able to  = can

这个,and 和什么平行? 看不到原题不大理解

没记错的话应该还是OG11上的一道原题

[原题] 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.

(A) 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.

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

(C) The new development of a 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 at a lower cost than the space shuttle.

(D) A newly developed 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 shuttle can, and at a lower cost.

(E) A newly developed 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 shuttle and to cost less.

(D) A newly developed 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 shuttle can, and at a lower cost.

(E) A newly developed 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 shuttle and to cost less.

其实，我看到了OG11th, verbal部分SC段第8题，也是如此。后面最后and at lower cost..