设备润滑的目的是在相对运动的两个接触面之间加入润滑剂从而使两

搜题请搜索小程序“爱下问搜题”

问题单项选择题

设备润滑的目的是在相对运动的两个接触面之间加入润滑剂从而使两摩擦为润滑剂（）间的内摩擦，达成减少摩擦的目的。

A.原子

B.分子

C.离子

D.电子

答案

参考答案：B

选择题

____ in the United States, St Louis has now become the 4^th largest city.

A．It is the 24^th biggest city

B．It was the 24^th biggest city

C．Before the 24^th biggest city

D．Once the 24^th biggest city

选择题

—The ice-cream is______ delicious.

—Yes, but don’t eat ______.

A．too much; much too

B．much too; too much

C．too many; much too

D．much too; too many