The computers made by our company sell best, but several years ago no one could have imagined the role in the markets that they ________.

A．were playing

B．were to play

C．had played

D．played

生产易燃易爆危险品的单位，对产品应当附有说明其危险性的( )。

A．提示标识

B．警告标识

C．说明书

D．注意事项