在but 后何时要接带to的不定式，何时要接不带to的不定式有一条简单的规则。那就是前面动词是do（does/did/done /doing/to do）时，后接不带to的原形不定式；如前面用的是其他的动词，则后面的不定式要加上to。

在这些动词do（does/did/done /doing/to do）在 but, except, save, than, as等词后，这条规则同样适用。

例如:  

He did nothing but laugh.

他只是笑。

What could he do but take back what he had said?

他除了收回他说的话以外，还有别的什么办法？

I did no more than make a beginning.

我只开了一个头罢了。

She did nothing else than cry all day.

她终日只是哭泣。

He did not so much as he was sorry.

他连一声对不起都没有说。

She seemingly has done nothing but accomplish the impossible。

他的神气好像是做成功了一件不可能的事儿。

Nothing remains but to die.

除死以外，别无办法。

We had no choice but to turn back.

我们除了转回去以外，别无选择。

They desire nothing but to enjoy the present moment.

他们只希望今朝有酒今朝醉。

You ought to know better than (to）believe all the gossip you hear.

你对情况的了解应该使你不会相信您所听到的一切谣言。

I am sure we had nothing to do but (to) fight the battle out。

我确信我们只有抗战到底，别无他法。