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

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