喉腔中最狭窄部位为（）
A.声门下腔
B.喉中间腔
C.喉咽腔
D.声门裂
E.喉室
参考答案：D
The newly published book, which refers ________ basic English grammar, is ________ only for beginners.
A．as; meant
B．for; intended
C．to; planned
D．to; intended
简述无效婚姻的概念和范围。
