它们非常有用。

They're very useful.

youdao

它们非常有用，比如说，能让我们更好地了解物质的表层属性。

They are very useful, for example, in understanding the properties of material surfaces.

youdao

XSLT还有许多其它变化，样式表程序员会发现它们非常有用。

There are many other changes to XSLT that style sheet programmers will find useful.

youdao

So again, these "Can" questions are very useful. You can use them in really any situation.

因此，“Can” 问句确实非常有用。你可以在任何语境中用到它们。

Can 课堂 - SpeakingMax英语口语达人