had best

used to suggest an action or to show that it is necessary

用于建议采取行动或表明有必要;最好

You had best tell her (= it would be wise if you told her) that you won't be able to come to her party.

你最好告诉她你不能参加她的聚会。

We'd best be going now (= we should go now).

我们最好现在就走。