导轨基本精度有（）项，它是保证机床各运动部件之间相对运动精度的关键。

A.一

B.二

C.三

D.四

. She_____ Japanese when she went to Japan for holiday. Now she can speak it freely.

A．picked up 　　

B．turned up　　

C．made up 　　

D．took up