请教GWD27-Q7中的一个小问题 - ChaseDream

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~~~