生殖器官发育最显著的时期是
A．新生儿期
B．幼年期
C．青春期
D．生育期
E．更年期
参考答案：C
The students often ________ games after school. They ________ volleyball now. [ ]
A. play, play
B. play, are playing
C. plays, are playing
D. are playing, play
第一个实现登陆月球的人是( )。
A．嫦娥 B．加加林 C．阿姆斯特朗 D．阿波罗
