首都剧场大厅内展示的头像雕塑是( )。
A．郭沫若和鲁迅
B．鲁迅和曹禺
C．老舍和曹禺
D．郭沫若和鲁迅
参考答案：C
—Do you know who cleaned the blackboard, Tina?
—Yes. John ______. [ ]
A. do
B. does
C. did
正向饱和电流是衡量二极管质量优劣的重要参数。
