the only修饰名词时，它后面习惯上可以加上动词不定式短语to do，动词不定式短语一般是用作后置定语的。例句：Mr. William is the only foreign friend to be present at the meeting.

the only相关例句

The only trouble is we won't be here then.

唯一的麻烦是到那时我们就不在这儿了。

The only stipulation is that the topic you choose must be related to your studies.

唯一的要求是你选的题目必须与你的研究科目有关。

The only people there were ourselves.

那里仅有的人就是我们自己。

We were the only people there.

我们是唯一在场的人。

That's the only reason I'm actually going.

这是我确实要走的唯一理由。