It is necessary for us to have a class meeting

有必要───be necessary

In several cases, additional sedation may be necessary.───对于严重的病例, 还必须镇静.

A little gentle prodding may be necessary at this stage.───在这一阶段或有必要稍微督促一下.

The ability to do this will be necessary in future flights to distant planets.───将来飞往遥远的行星时,需要这样的能力.

Such tilting will be necessary.───这种改变是必需的.

How much alteration will be necessary?───需要改多少?

Sampling of propellants under typical operating conditions may be necessary to obtain valid capacitance information.───为了获得有效的容量资料,在典型的工作条件下对推进剂取样是很必要的.

Spraying with insecticides and fungicides may be necessary to control any insects and diseases.───也许有必要喷洒杀虫剂和杀菌剂以防止病虫害.

I kept the engine running because it might be necessary to leave fast.───我没让发动机熄火，因为也许需要迅速离开。

To join these two pieces of metal, it will be necessary to heat them.───要把这两块金属接合起来, 就要将它们加热.

Now, Mr. Willis . I'm sure that won't be necessary.───哦, Willis先生, 我认为没这个必要.

It may be necessary to make alternative arrangements.

Irrigation measures will be necessary in areas of erratic rainfall.

Some adjustment of the lens may be necessary.

At least a year's preparatory work will be necessary before building can start.

It will be necessary to proceed with caution.

It may be necessary to buy a new one.

I don't think that will be necessary.

If God did not exist, it would be necessary to invent Him. 

It may be necessary to thin the sauce slightly.