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问题 填空题
设i是虚数单位，则
i
1-i3
=______．
答案

i
1-i3
=
i
1+i
=
i(1-i)
(1+i)(1-i)
=
1+i
2
=
1
2
+
1
2
i

故答案为：

1
2
+
1
2
i

句型转换

按要求完成任务。

1. My sister does her homework every evening. (改为一般疑问句)

    ________ your sister ________ her homework every evening?

2. John has lunch at school. (改为否定句)

    John ________ ________ lunch at school.

3. I play computer games once a month. (就划线部分提问)

   ________ ________ do you play computer games?

4.We go to school at seven thirty. (改为同义句)

    We go to school at ________ ________ seven.

5.The tiger need 6 kilos of meat a day. (就划线部分提问)

   ________ ________ meat do the tigers need a day?

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多项选择题

螺纹钢性能指标包括（）。

A、肋高

B、强度

C、延伸率

D、内径
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