At the beginning of class, the noise of desks _______could be heard outside the classroom.
A.opened and closed
B.to be opened and closed
C.being opened and closed
D.to open and close
网友回答
C解析思路分析：句意为：在刚开始上课时，课桌打开和关上的噪声在教室外面就听到。the desk与open和close是被动关系，且表示打开和关上的动作正在进行。故选C。
【点评】本题考查了分词的时态，难度较大。做本题时一定看清修饰和被修饰两者之间是主动关系还是被动关系，且注意此动词表过程还是表正在进行。