我12歲了用英語怎麼表達

In those days most people left school when they were only fifteen years old.

那時候，大多數人上學只上到十五歲。

He is ten years old.

他十歲了。

At thirty years old, he was already earning  40 000 a year.

他三十歲時已拿到4萬英鎊的年薪了。

You don't look 15 years old

你看上去不像15歲。

At 54 years old her energy and looks are magnificent

她54歲了，精力和氣色都非常好。