My brother is three years old.

我的弟弟三岁了。

Her daughter just turned three years old.

她的女儿刚刚三岁。

These toys are suitable for children over three years old.

这些玩具适合三岁以上的孩子。

I am twenty-three years old.

我今年二十三岁。

She lived to be seventy-three years old.

她活到了七十三岁。

This child is only three years old, but can already count.

这个孩子只有三岁，但已经会数数了。

The toy is labeled as noa for children under three years old.

这种玩具被标示为对三岁以下儿童无害的。

When I was three years old, I learned to ride a bike.

当我三岁时，我学会了骑自行车。

I remember my birthday party when I was three years old.

我记得我三岁时的生日派对。

He could find the way home though he was only three years old.

虽然他只有三岁，但他能找到回家的路。