Why not后面加“原形动词”。例如：
Why not go skiing with us?
这是个“征询对方意见”的问话。另外还有：
Why go out to play football?(why 后面也是直接加原形动词)
why和其它特殊疑问词接动词的时候不同.例如：
What to do tomorrow isn't decided yet.
When doing some washing， I was listening to the English programs.
why not加to do还是加doing
why not加to do
why not do sth.为什么不做某事
why not doWhy don't 后加人称、谓语如：Why don't you take a bus?Why not take a bus?
why not及why don't you，还有一种是经常合他们互换的，是：how about 和what about ，二者可以互换，后面加doing sth.
why not do sth =why don't sb do sthsb don't do sth你可以理解吧
