It may be necessary to buy a new one.

也许有必要买个新的了。

It may also be necessary to get a new appraisal of the property.

可能还需要对该房产做个新的估价。

I kept the engine running because it might be necessary to leave fast.

我让发动机一直开着，因为可能需要快速离开。

It might be necessary to make a few slight modifications to the design.

也许有必要对这个设计稍作几处修改。

It might also be necessary to supply an abstract of the review of the literature as well.

可能也有必要提供这篇文学评论的摘要。