两道题的比较

1. The gyrfalcon, an Arctic bird of prey, has survived a close brush with extinction; its numbers are now five times greater than  when the use of DDT was sharply restricted in the early 1970's.

A. extinction; its numbers are now five times greater than

B. extinction; its numbers are now five times more than

C. extinction; its numbers now fivefold what they are

D. extinction, now with fivefold the number  they had

E.  extinction, now with five times greater than

2.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. high-paying fields like electronics and banking, and make the state's economy far more diversified than it was.

我觉得这两道题都是现在和过去进行比较，但是为什么第一道题选a，第二道题选d,第一道题和过去的比较为什么能省略掉they were， 而第二道就不能省略?谢谢各位

可能是因为例一中than 后面是when引导的状语从句，其中已有was出现说明是1970's时的状态

如果when前再加上they were感觉重复且笨拙。楼主可以去搜一下以前的讨论贴看一看