某人用尖锐的器具掏挖“耳屎”，不小心戳穿某结构导致耳聋。该结构可能是[ ]
A．耳廓
B．咽鼓管
C．鼓膜
D．半规管
答案：C
-Where is your friend?
-I __________ he's at home.[ ]
A. look at
B. know
C. see
D. think
口服胆囊造影法可观察胆囊的_______和_______功能。
