PQS起升机构控制屏，下降第三档为（）制动。
A.反接
B.单相
C.回馈
参考答案：C
Was it ______ he was playing volleyball on the playground_________ he got hurt?
A．that; when
B．when; that
C．that; where
D．where; that
矩形截面导体竖放比平放散热效果（）。
A.好
B.差
C.一样
D.可好可差
