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问题 选择题

下列判断正确的是[ ]

A．x2=9x的解是x=0

B．（x+1）（x﹣1）=1的解是x=±1

C．2x2﹣3x是一元二次方程

D．6x2﹣1=3x的一次项是﹣3x

答案

答案：D

单项选择题

垫厚度将上下前牙离开多少最为适宜（）

A.3mm

B.5mm

C.0.5～1mm

D.0.3～0.5mm

E.1.5～2mm
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填空题

根据句意、汉语或首字母提示，补全单词，完成句子

1. Friends often s_____ hands when meeting each other.

2. Jack was s_____ to arrive at 7:00, but he arrived at 9:00.

3. In Japan people like to b_____ to each other when meeting for the first time.

4. How do you _____ (打招呼) other people in your country?

5. In _____ (瑞士) it is very important to be punctual.
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