表面淬火和化学热处理都能改变钢的表面成分和组织。
参考答案:错
--Did you buy _______ special for your parents? -- Yeah. But I bought ______ for myself.
A.anything; something
B.something; nothing
C.something; something
D.anything; nothing
在发动机停机的状态下,定点火器输入电压。此电压值约为()V。
A.12
B.5
C.24
D.42