its:

pron. 它的Its claws lacerated his thighs.

它的爪子挠伤了他的大腿。

Its skin feels really smooth.

它的皮摸起来真光滑。

I was astounded by its beauty.

我被它的美丽震撼了。

The film has its moments.

这部电影有它走红的时候。

theirs:

pron. 他们的I think she's a relation of theirs.

我想她是他们的亲戚。

It's a favourite game of theirs.

这是他们最喜爱的游戏。

It was a neighbourly gesture of theirs.

这是他们友好的表示。

Theirs are the children with very fair hair.

他们的孩子是那些长着满头金发的。

Our children go to the same school as theirs.

我们的孩子和他们的孩子上同一所学校。