由OG198想到的比较句型中的省略

为什么比较句型中有这么多的省略呢？而且好像都是喜欢省略比较从句中的比较对象，很是让人迷惑！！！如果比较从句是划线部分，且选项中既有省略形式又有补充了比较部分（代词或名词），那我们应该选哪个呢？

参考：

198. Although Napoleon's army entered Russia with far more supplies than they had in their previous campaigns, it had provisions for only twenty-four days.

(A)  they had in their previous campaigns

(B)  their previous campaigns had had

(C)  they had for any previous campaign

(D) in their previous campaigns

(E) for any previous campaign

正确选项是E,

than 后面怎么没有that这样的代词呢？这边的than是怎么用法呢？？

NN回答：

than 后面怎么没有that这样的代词呢？这边的than是怎么用法呢？？army entered Russia with far more supplies than (supplies) for any previous campaign

187. In one of the bloodiest battles of the Civil War, fought at Sharpsburg, Maryland, on September 17, 1862, four times as many Americans were killed as（they） would later be killed on the beaches of Normandy during D-Day.

(A) Americans were killed as

(B) Americans were killed than

(C) Americans were killed than those who

(D) more Americans were killed as there

(E)  more Americans were killed as those who

（1）有NN说：as后面省略了they；（2）另一种解释：as 可以做比较从句的主语。

虽然不能确定是哪种解释，但是至少有省略的嫌疑！

请NN帮忙CONFIRM一下，1、比较句型中比较从句省略的问题

                                           2、OG187中到底是哪种解释？

谢谢了