Shila doesn't speak our language,              she seems to understand what we say.

A．and

B．yet

C．so

D．or

圆锥破碎机冷却器前后油流温差过小的原因是（）。

A、油泵扬量不足

B、油压不够

C、循环冷却水不足

D、稠油过多