Unless you speak English yourself, you’d better take a translator with you.

A．If you speak English yourself, you’d better take a translator with you.

B．you’d better not take a translator with you if you speak English.

C．You’d better take a translator with you if you don’t speak English yourself, .

D．If you don’t speak English yourself, you’d better not take a translator with you.

低速及间歇工作设备，其轴和轴瓦的接触点为每平方厘米（）点。

A.1~1.5

B.2~3

C.3~4

D.4~5