请教GWD27-Q7中的一个小问题

GWD27-Q7

Providing initial evidence that airport are a larger source of pollution than they were once believed to be, environmentalists in Chicago report that the total amount of pollutant emitted annually by vehicles at O’Hare International Airport is twice as much as that which is being emitted annually by all motor vehicles in the Chicago metropolitan area.

A.      as much as that which is being emitted annually by all
                       

B.       as much annually as is emitted by the

C.      as much compared to what is annually emitted by all

D.      that emitted annually by all

E.       that emitted annually compared to the

答案是D， 可是谁能告诉我  A is twice as much as B ,这个比较中第二个AS 后面可以跟句子吗？第2个AS是连词吗？B 的错误在哪？谢谢~~~

A 中的不是句子吧，我把它想成 that指代里面的number，后面which从句是修饰that的。 像ls的ls说的，应该是错在being吧。

please check OG11-85, OG-128

Then you will find some clues