引起大气运动的根本原因是 

A．地面辐射

B．高低纬度之间的热量差异

C．同一水平面上气压差

D．地转偏向力

根据句义，用括号中所给词的适当形式填空。

1. John and Mike ___________ kites near the river now. (fly)

2. It's expensive ____________ to other countries. (travel)

3. Jim _____________ not cook five years ago. (can)

4. The _____________ day of May is his birthday. (twelve)

5. He enjoys _____________ tricks on his friends. (play)