二十一的用法和樣例：
例句
-
他數了一下在場(chǎng)的人數，結果共有二十一人。
He counted the number of people present and fetched up with twenty-one. -
把書(shū)翻到第二十一頁(yè)。
Open your book at Page twenty-one. -
我已經(jīng)過(guò)二十一周歲了。
I was twenty-one on my last birthday. -
這筆錢(qián)委托他人代管，到他二十一歲才能使用。
The money is being held in trust for him until he is twenty-one.
