His father got him a job in a bank but soon it became clear ______ he was not fit for that kind of work．

A．why

B．what

C．whether

D．that

根毛细胞能够吸水的原因是（　　）

A．根毛细胞数量多，吸收面积大

B．根毛细胞与土壤溶液相接触

C．液泡大，细胞液浓度大于土壤溶液浓度

D．液泡小，细胞液浓度小于土壤溶液浓度