C
答案C是错误的。因为leave不是延续性动词,在现在完成时态中不能与一段时间状语for over twenty years连用。而答案D是正确的。主动句可为:I heard him singing a pop song when I passed his room.
C
答案C是错误的。因为leave不是延续性动词,在现在完成时态中不能与一段时间状语for over twenty years连用。而答案D是正确的。主动句可为:I heard him singing a pop song when I passed his room.