what

what we should do is后面通常接to do，但to经常被省略，如：What we should do is to buy another computer或What we should do is buy another computer。

what we should do is后面接形容词如：what we should do is very important。接动名词如：what we should do is studying。接不定式如：what we should do is to study hard。接表语从句如what we should do is that we should study hard。