机床工作结束后,应最先做哪些安全工作?()
A.清理机床
B.关闭机床电器系统和切断电源
C.润滑机床
D.清洗机床
参考答案:B
-- I know this is the latest type but it's secondhand. $20 -- that's my last offer.
-- OK. It's a(n) ___________.
A.business
B.trade
C.agreement
D.deal
起货电动机应为防()式的防护形式,和()工作制的电动机。
A.水;短时
B.水;重复短时
C.护;短时
D.护;重复短时