其中的 to 可以省略，也可以保留。如：

All I did was (to) press the button. 我只是按了一下按钮。

What you have to do is (to) fill in the questionnaire. 你要做的是把问卷填好。

The first thing to do was to have a meal. 第一件该做的事是吃饭。

What you have to do is to choose a company to invest in. 你需要做的是选一家公司投资。

Our mothers sat us down to read and paint, when all we really wanted to do was to make a mess. 我们的母亲让我们坐下来读书和画画，而我们真正想做的却是打打闹闹。

All he needs to do is make one phone call and I’m a marked man. 他只消打一个电话，我就大难临头了。

All the newspapers really want to do is scoop the opposition.  所有报社真正想做的就是比对手抢先报道。