necessary高级词汇

Necessary.的高级词汇有： essential, indispensable. critical , vital, crucial, inevitable

关于 necessary 的用法，请记住以下几条:

1.be necessary for somebody to do…

It's necessary for us to buy a car.

2. If it is necessary.常常被简化为if necessary,

If necessary, you can contact me at school.