三道语法题，请帮忙解释一下！谢谢！

1.        A huge flying reptile that died out with the dinosaurs some 65 million years ago, the Quetzalcoatlus had a wingspan of 36 feet, believed to be the largest flying creature the world has ever seen.

            (A) believed to be

(B) and that is believed to be

(C) and it is believed to have been （什么时候用Which,什么时候不用呢？）

(D) which was, it is believed,

(E) which is believed to be

2.        A Labor Department study states that the numbers of women employed outside the home grew by more than a thirty-five percent increase in the past decade and accounted for more than sixty-two percent of the total growth in the civilian work force.

(A) numbers of women employed outside the home grew by more than a thirty-five percent increase

(B) numbers of women employed outside the home grew more than thirty-five percent

(C) numbers of women employed outside the home were raised by more than thirty-five percent

(D) number of women employed outside the home increased by more than thirty-five percent （为什么选这个？为什么不是B?一定要用by吗？）

(E) number of women employed outside the home was raised by more than a thirty-five percent increase

3.        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

(B) and make 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 （为什么A不可以呢？）

(D) to make the construction industry’s economic health much more robust than five years ago

(E) in making the construction industry’s economic health much more robust than it as five years ago

个人观点啊，

第一题我做过，我是这样选对的：A believed to be 修饰了wingspan 显然和后面的creature 不一致

B that貌似有点指代不明啊，不知道说的是前面的现象呢还是什么，而且和C选项中的完成事态相比，这个一般现在时与从句the world has ever seen不对应，要用be believed to have been 因为这种恐龙是迄今为止世界上见过的最大的,而且这种恐龙已经灭绝了，现在不存在了，只能用完成时

C 对的，it指前面的那只恐龙。

D 很显然不对，如果which指代前面那只恐龙，那it 就有点不知所云，好像是重复累赘了

E 时态问题可能不容易察觉的，但是这边很明显的，which是指代那个，如果指代那只恐龙，是不是属于遥远指代，如果是指代wingspan，意思就不清楚了

第二题，你看ABC 选项中的the numbers of是不符合习惯用法的，肯定要排除的，至于要不要用by 我也有点混淆。。。

A economic health 直接跟five years ago 比肯定是不可以的，东西怎么能和时间比呢？只能说是现在的经济健康跟五年前的相比啊

多谢！！！明了了：）