回火的目的是什么?
参考答案:
(1)、减少和消除钢体在淬火后所产生的内应力,稳定组织;
(2)、减少脆性,提高韧性和弹性;
(3)、获得零件所需要的性能。
句型转换。
1. The young lady will have to look after her sick child at home.(改为同义句)
The young lady will have to__________ __________ __________ her sick child at home.
2.You should buy me a new car.(改为同义句)
You should ___________a new car __________ me.
3.Tom should tell him the story.(改为否定句)
Tom __________tell him the story.
4.I found it was easy to get on with others.(改为反义句)
I found__________ _________to get on with others.
5. The dictionary cost me fifty yuan.(改为同义句)
I ___________fifty yuan ___________the dictionary.
下列关于汉字起源的说法错误的是()。
A、结绳记事说
B、瓷器符号说
C、源于图画说
D、其余八卦说