蜗杆一般是用()制作的,高速重载蜗杆常用()或()渗碳淬火。
参考答案:钢;15Cr;20Cr
— Excuse me, could you tell me where I could make a call?
— Sorry, I’m a stranger here.
— ________.
A.Thanks a lot
B.That’s a pity
C.Thanks anyway
D.I’m sorry to hear it
喷雾的形成机理是燃料受()的压缩,在高压下从喷油器喷孔喷出,便形成喷注。
A.喷油泵
B.喷油器
C.出油阀
D.喷油嘴