用所给词的适当形式填空。

1. Li Ping decided ____________ (make) his breakfast.

2. Please help the children ____________ (do) their homework.

3. I found the little girl ____________ (cry) in the corner.

4. ____________ (not take) a shower when you are ill in bed.

5. Let's ____________ (buy) some hamburgers and soda.

6. We had fun ____________ (swim) in the water yesterday afternoon.

7. His father made him ____________ (go) to bed before 10:00 every evening.

8. Every student wants ____________ (clean) the classroom.

9. One of the animals ____________ (be) very friendly and intelligent.

10. Who can ____________ (write) an English article?

11. Listen! She ____________ (sing) in the next room.

12. He ____________ (see) the police officer last night.

穿过半圆形的两个金属板，板间存在着辐向均匀分布的电场（电场线背离圆心），有一束负离子由a沿半圆弧虚线运动到b，如右图所示，则这些粒子可能具有（　　）

A．相同的电量和质量

B．相同的电量和动能

C．相同的电量和速度

D．相同的质量和速度