问题
单项选择题
下列热处理工艺的冷却速度关系描述正确的是（）。
A．退火＜回火＜淬火
B．回火＜退火＜淬火
C．淬火＜回火＜退火
D．退火＜淬火＜回火
答案
参考答案：A
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下列热处理工艺的冷却速度关系描述正确的是（）。
A．退火＜回火＜淬火
B．回火＜退火＜淬火
C．淬火＜回火＜退火
D．退火＜淬火＜回火
参考答案：A
| 根据句意从方框中选用合适的词语，并用其适当形式填空。 | |
2. It's good to help others when they are _____. 3. Don't keep _____. Be careful when you are doing your homework. 4. My host family often _____ their way to make me feel at home. 5. In Switzerland, people usually _____ to meet friends. |