已知，点C是线段AB的中点，且AB=20cm，则AC=______cm．

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问题填空题

答案

∵点C是线段AB的中点，且AB=20cm，

∴AC=

AB=

×20=10cm．

故答案为：10．

补全对话，情景问答

根据对话内容及首字母提示，在每个空中填入适当的词语，完成对话。

A: Good morning. Li Fang. .

B: Good morning, Liu Mei. Look, there is a book over there.

A: Oh, it's a French book.

B: W 1 book is it, do you know?

A: I think it could be Li Lei's. He loves French very much.

B: No, it c 2 be his. He has been away f 3 school for several days.

A: Is it Chen Qiang's?

B: I d 4 think so. You know he doesn't like French at all.

A: Oh, I know. It m 5 be Deng Ping's. Look, it has her name on it.

B: I think you are right. Let's g 6 it back to her.

A: OK. Let's go.

1. 2. 3. 4. 5. 6.

判断题

从总体中按随机原则抽取出来的部分单位所组成的集合体称为样本。（）