________ Pierre began to help his father with the farm work when he was        

A．In 1980’s; his teens

B．At the 1980’s; the teens

C．In the 1980s; in his teens

D．In 1980’s; in the teens

第一代计算机主要特征是逻辑部件采用______。

A．电子管

B．晶体管

C．中小规模集成电路

D．大规模和超大规模集成电路