若圆锥的母线长为5，底面半径为3，则圆锥的侧面积等于.

There are a lot of things ______ at school. [ ]

A. to do

B. doing

C. do

D. does

I need to       my colleagues on the proposals.Some days later,I will tell you the result. [ ]

A.consult with

B.talk about

C.speak of

D.tell from

井筒内液面凝结成死油盖子时，必须采用（）措施来解除。

A、热洗

B、刮削

C、通井

D、上提

简述HXN5型机车的控制系统？

钢坯加热后一端温度低，一端温度高的原因是什么？如何解决？