排球运动开展的最晚、水平最低的是（）。
A、亚洲
B、非洲
C、欧洲
D、美洲
参考答案：B
在一个生态系统中，具有锐利的牙齿和尖锐的爪的动物常常是[ ]
A．初级消费者
B．次级消费者
C．自养生物
D．分解者
The students often ________ games after school. They ________ volleyball now. [ ]
A. play, play
B. play, are playing
C. plays, are playing
D. are playing, play
