A great number of students        said they were forced to practice the piano.

A．to question

B．to be question

C．questioned

D．questioning

上颌窦底壁为（）。

A.翼腭窝、颞下窝

B.尖牙窝

C.眼眶底部

D.牙槽突

E.鼻腔外侧下部