Clothing made of man-made materials has advantage over _________ made of natural ones like cotton, wool or silk.

A．one

B．it

C．that

D．the ones

如果发现从浸入式燃油增压泵的滴油管中滴出过多的燃油则表明：（）.

A.油泵叶轮损坏。

B.油泵电机的封严圈损坏。

C.油泵与油箱连接处的封严损坏。

D.油泵出口单向活门堵塞。