他们是谁：Who are they?
例句：
许多孩子知道他们是谁，可就是不说。
Many of the children know who they are but are not telling.
现在拥有一个家庭是另一回事,因为你不能随心所欲地选择他们是谁。
Now having a family is a different thing because you cannot choose who they are as you want.
通常他们是为谁来支付账单而争吵。
Mostly, they fight about paying bills.
他们试图找出是谁出卖了他们。
They tried to find out who had ratted on them.