某多边形的外角和等于其内角和的一半，则这个多边形的边数是____

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问题填空题

某多边形的外角和等于其内角和的一半，则这个多边形的边数是______．

答案

多边形的内角和是：2×360=720°．

设多边形的边数是n，则（n-2）•180=720，

解得：n=6．

即这个多边形的边数是6．

单项选择题

有关接种环的灭菌方法，错误的是()

A．接种环常用火焰灭菌，也可用消毒

B．接种环使用前必须先灭菌

C．火焰灭菌后，须待环冷却方可取菌(标本)

D．染菌的接种环先于内焰加热、烤干，再移至外焰灭菌

E．接种环用完后，应立即搁置于架上，勿随手弃置

填空题

用所给词适当形式填空：

1. The men in _______ (制服) came up to them

2. When you come to the ________ (拐角), turn right.

3. He ran ________ (朝，向) the car that was moving.

4. Are you ________ (惊讶的) to see the animals?

5. My mother was ill yesterday and she felt very ________ (虚弱的).

6. Can you swim ________ (cross) the river.

7. The problem is very easy. They can work it out ________ (easy).

8. He went to school without ________ (have) breakfast.

9. They ________ (plan) to take another route when they saw the robbers.

10. We'll learn the ________ (twelve) lesson tomorrow.