赞同曹老师的解答。其实，may/might as well do sth.与had better do sth.还是有区别的。

may / might as well“最好，不妨，还是……好”，表消极或无奈；had better...“最好……”，表主动或积极。例如：

Since he won’t listen to you, you may as well let him be. 既然他不听你的，那就随他去吧。

Anyway, you're here; you might as well stay. 反正你已经在这儿了，那就留下来吧。

      might as well do sth 和 may as well do sth 是习语，主要有两种用法：

     （1）表示因为某事不能避免或者没有合适的理由不做而应该做或者接受，通常译为“应该做某事”、“最好做某事”。如：You might as well tell them the truth. 你应该告诉他们实情。/ We may as well begin now. 我们最好现在就开始。/ They're not going to change their decision,so you might (just) as well get used to it. 他们不会改变决定的，所以你最好还是服从吧。/ (informal)“Should we start now ?”“Might as well.”“我们现在开始吗？”“最好开始吧。”

    （2）表示做另外的实情（实际上没有做）也会有同样的效果，通常可以译为“还是...的好；倒不如（做另外的事情）”：The party was so dull that I might (just) as well have stayed home. 那次聚会太无聊了，我还不如待在家里。

  （以上例句摘自《韦氏高阶英汉双解词典》p.2375）