下列“家庭小实验”可以达到实验目的的是（       ）

A．用铅笔芯试验石墨的导电性

B．用食盐水除去热水瓶中的水垢

C．用淬火后的钢针做钓鱼钩

D．用铜导线和食醋制氢气

She ________ Japanese when she was in Japan. Now she can speak it freely.[ ]

A．picked out  

B．made out

C．made up  

D．picked up