(2011·重庆)It is still under discussion ________ the old bus station should be replaced with a modern hotel or not.

A．whether

B．when

C．which

D．where

肺内气体交换的面积大的原因是肺泡（　　）

A．数目多体积小

B．数目少体积小

C．数目多体积大

D．数目少体积大