智慧职教: ______ cannot be hardened by heat treatment since they contain no hardening element.
举一反三
- The precipitation hardening processes include （） heat treatment and （） heat treatment.
- In which heat treatment process, the specimen should be cooled in water or oil A: Tempering B: Annealing C: Quenching D: Case hardening
- _____ is the first element on the periodic table, making it the lightest element. Since it is so light, it rises in the atmosphere and is therefore rarely found in its pure form.
- I end up getting my heart ______ . For so many years, I was never expressive with my feelings. A: hardened B: hardening C: hardens D: being hardened
- The red, orange and yellow lights contain ______. A: less heat than the other lights B: more heat than the other lights C: a great deal of heat D: a little heat