The car ran down the hill, and the driver _____, according to the newspaper, to have been killed.

A．said

B．was saying

C．was said

D．had been said

对于悬浮液而言，固相体积浓度的上限不超过30%～35%，下限不宜超过（）。

A、20%

B、10%

C、15%

D、25%