单项选择题
Peter was about to unlock the door ____he found someone...
单项选择题Peter was about to unlock the door ____he found someone had broken into the room.( )
空调系统空气处理机组的粗过滤器应装在( )。A.新风段B.回风段C.新回风混合段D.出风段
单项选择题空调系统空气处理机组的粗过滤器应装在( )。
老生杨派的艺术特点是善于演唱高音。A.正确 B.错误
不定项选择老生杨派的艺术特点是善于演唱高音。