it's的复数形式是they're。they're的例句：I think we caught them with their pants down，They're a bit confused（我觉得我们让他们下不了台了，他们有点不知所措）。

they're的例句：But I put it to you that they're useless（但是我告诉你它们是没用的）；People eat when they're depressed（人在心情沮丧时就吃东西）。