阴茎 ( )
A．由三个阴茎海绵体构成
B．阴茎海绵体内有 * * 通过
C．阴茎脚附着于耻骨弓
D．阴茎脚附着于尿生殖膈
参考答案：C
大气圈的空气由氮气和氧气两种气体组成______．
用括号内所给词的适当形式填空。
1. Mary happened to meet one of her old friends and invited him ____ (go) to her new house.
2. They are getting ____ (marry) next month, so they are very excited now.
3. You will feel unhappy when someone ____ (smile) at you in a strange place.
4. Mr. Smith seems to be ____ (please) with the new student called John.
5. The lights are off. I think there was nobody ____ (leave).
