[求助]再问代词it的指代问题

49.       (27096-!-item-!-188;#058&003405)

Since 1990 the global economy has grown more than it did during the 10,000 years from the beginning of agriculture to 1950.

(A) Since 1990 the global economy has grown more than it did during the 10,000 years from the beginning of agriculture

(B) Since 1990 the growth of the global economy has been more than that during 10,000 years, from when agriculture began

(C) The growth of the global economy since 1990 exceeds that which had been for 10,000 years from the beginning of agriculture

(D) The growth of the global economy since 1990 exceeds what it has been for 10,000 years, from when agriculture began

(E) The growth of the global economy since 1990 exceeds what it did for the 10,000 years from the beginning of agriculture

95.       (29501-!-item-!-188;#058&004299)

Officials in Atlanta's public schools, as do many districts across the United States, have eliminated recess in the elementary grades, calling it a waste of time that would be better spent on academics.

(A) as do

(B) as with

(C) similar to

(D) like those in

(E) as they have in

Although people in France consume fatty foods at a rate comparable to the United States, their death rates from heart disease are far lower in France.

A. people in France consume fatty foods at a rate comparable to the United States, their

B. people in France and the United States consume fatty foods at about the same rate, the

C. fatty foods are consumed by people in France at a comparable rate to the United States's, their

D. the rate of fatty foods consumed in France and the United States is about the same, the

E. the rate of people consuming fatty foods is about the same in France and the United States, the

There are hopeful signs that we are shifting away from our heavy reliance on fossil fuels:  more than ten times as much energy is generated through wind power now than it was in 1990.

(A) generated through wind power now than it was

(B) generated through wind power now as it was

(C) generated through wind power now as was the case

(D) now generated through wind power as it was

(E) now generated through wind power than was the case

前面三道题都是做陪衬的，就是想对比什么时候代词可以使用，什么时候没戏。第一题的it指代growth可以，因为growth没有被限定修饰为90年的，所以也可以指50年的。后面两道不可以，因为有in做定语限定修饰。

那么我的问题是这最后一道题的it使用是否正确？解释说it使用错误，因为it特指当今被风力产生的能源。可是大家看看，energy被限定修饰了么？窃以为这么说不妥。。。。

是故，我也没找到b项错在哪了，只是觉得c项比较爽一点。。。。

想了将近10分钟.愣是没想明白.

期待版主答复~

要永恒的东东才能用It指代?

嗯...大概明白了.

就是it指代的东西不能是一直在变化的东西.

但问题又来了,碰到一些intangible的东西, 例如economy,又或者一些流动的东西, water, air, or light in a specific area, 它们可以用it指代吗?