12Cr1MoV是(),一般对其焊接接头()进行热处理。
参考答案:耐热钢;要
什么叫做热对流?
Questions 81-90 are based on the following passage.
The passage is primarily concerned with ______.
A. informing readers of different sea creaturesB. describing predatory microscopic organismsC. solving some long-lasting mysteries about the seaD. discussing the environment for various fishes