“That VCD you bought ____ very expensive” . “Do you know ____ ? ”

A．ought to be ; how much it cost

B．may be ; how much it costs

C．must be ; how much it cost

D．can be ; how much doesn''t it cost

安装滑动测微计时，要在钻孔内安装（）。

A、钢导管；

B、测标导管；

C、有槽子的导管；

D、可变形的塑料管。