已知一齿轮的制造工艺过程是:加工齿坯、滚齿、表面淬火和磨齿,则该齿轮的材料是()。
A.20CrMnTi
B.40Cr
C.Q235
D.ZCuSn5Pb5Zn5
参考答案:B
体内蛋白质代谢的终产物是()
A.乳酸
B.胆红素
C.尿素
D.尿酸
E.肌酐
Generally speaking, how many students fail this course
A.A few.
B.Many.
C.None.
D.All.