比较结构状语比较的问题

dypig1234

看过比较庖丁解牛的文章，关于这个考点本来还是挺清晰的，

总结中给的例句：Rice has protein of higher quality than 5 years ago.

旧Prep上也有一道状语比较的句子：……the plant's curst harbors up to three times as much as previously thought.

可是，做大全的时候被一道题弄晕了，题目如下：

大全第10题（补充170题）

10.    A large rise in the number of housing starts in the coming year should boost new construction dollars by several billion dollars, making the construction industry’s economic health much more robust than five years ago.

(A) making the construction industry’s economic health much more robust than five years ago
(C) making the construction industry’s economic health much more robust than it was five years ago

The key is C.

这里为什么要加“it was”呢？ 首先，我觉得这道题完全从语义上可以理解为状语的比较（这里是不同时间段的robust程度的比较吧）啊？！其次，就算理解成是make的宾语比较，it指代the construction industry’s economic health ，那这个“was”是哪里来的呢，做什么成分呢？前面找不到与was对应的东西啊？？

困惑好久了～希望帮帮忙，解答下哈

triangel8866

我觉得是这样理解。
这里主结构是make health more robust than it was five years ago，用的是make＋n.＋adj.的结构，robust作health的宾补修饰宾语。其宾语与宾补的关系就是n.+be+adj.
而省略有很重要的一点就是相同部分可以省。这里是补出了it was省略了robust，明确表明发生在过去，而不是had been或will be。我记得不同时间的比较一般都补出助动词的，经常看到主句是did，than后面是had的结构。
其实这题我也是知道答案后倒推的，一上来也选的A。
在下一点拙见，望能有帮助。

triangel8866

299.Florida will gain another quarter-million jobs this year alone, many of them in high-paying fields like electronics and banking, making the state’s economy far more diversified than ten years ago.
(A) high-paying fields like electronics and banking, making the state’s economy far more diversified than
(B) high-paying fields like electronics and banking, and making the state’s economy far more diversified than its economy
(C) high-paying fields such as electronics and banking, to make the state’s economy far more diversified than
(D) such high-paying fields as electronics and banking, making the state’s economy far more diversified than it was
(E) such high-paying fields as electronics and banking, and make the state’s economy far more diversified than it was

OA
看来it was还是要补的。

ChinaHawk

时态相同可以省，时态不同必须补