while连接 两个句子

GabrielHJ

46.   (26975-!-item-!-188;#058&003041)

The continental United Statesreceives an average of 30 inches of precipitation a year; transpiration fromsoil and from plants returns approximately 21 of the 30 inches to theatmosphere, while the balance of 9 inches contributes to the flow ofstreams and rivers.

(A) transpiration from soil andfrom plants returns approximately 21 of the 30 inches to the atmosphere, whilethe balance of 9 inches contributes to the flow

(B) even though transpiration fromsoil and from plants returns approximately 21 of the 30 inches to theatmosphere, the remainder of 9 inches contribute to the flowing 主谓不一致

(C) although transpiration fromsoil and from plants return approximately 21 of the 30 inches to theatmosphere, the balance of 9 inches contribute to the flowing

(D) with transpiration from soiland from plants to return approximately 21 inches to the atmosphere, the restof the 9 inches contributes to the flow

(E) as transpiration from soil andfrom plants return approximately 21 of the 30 inches to the atmosphere, therest of the 9 inches contribute to the flow

A正确
while连接句子的时候不是表示转折么？但是A中前后两个句子没有转折的意思呀，为什么A正确。

kiwifoodtown

连词while，有“。。。而。。。。”，“在。。。同时。。。。”，“在。。。。期间。。。”等几种意思，LZ自己去琢磨这里应该是什么意思。