将钢件加热到AC3或AC1以上某一温度，保持一定时间。然后以适当速

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问题填空题

将钢件加热到AC3或AC1以上某一温度，保持一定时间。然后以适当速度冷却获得M或B下组织的热处理工艺称为（）。

答案

参考答案：淬火

写作题

Dongtai	In the past	At present
Environment	narrow and dirty roads, rubbish everywhere, large open spaces	wide and clean streets , green trees on both sides , shops and tall buildings
Life	small old houses , listen to the radio or watch TV	new flats , computers and the Internet , mobile phones
Transport	on foot or by bicycle	by bus or taxi , have own cars
Opinion	enjoy a comfortable life

填空题

退行信号鸣笛方式是：（）。