问题
选择题
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
答案
C。
由于是用于介词of后作宾语,所以要用动名词,不用不定式或过去分词,故选C。另外,由于desks与open和close的关系是被动关系,故要用动名词的被动式being opened and closed。