— How many gold medals did China            at the 2010 Winter Olympics?

— Five. [ ]

A. win

B. to win

C. winning

D. won

风动打锈锤的端部有梅花形凸出的棱角，锤的往复运动是由压缩空气驱动的，所需压缩空气的压力为( )。由于锤的往复运动撞击金属表面铁锈，从而达到除锈目的。

A．0.3～0.6MPa

B．0.4～0.6MPa

C．0.4～0.7MPa

D．0.3～0.5MPa