prep2-49, from when

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

答案是A

我有两个问题呢

第一个就是from when 为什么错呢？为什么from后面一定要跟名词，还有就是when agriculture began 不可以充当名词吗？比如说when you come here really matters a lot. 这里面的when you come here不就是作为句子主语吗？当然就是名词了

第二个就是from the beginning of agriculture to 1950 两个都是过去的时间，应该用过去完成时呀？这里为什么要用过去时呢？

回帖的先谢过