IN: Which person is he?
Jean is making fun of Kyle because he lost.
OUT: Kyle

IN: Which person is they?
Bioware recently announced a stress test to beta users this weekend since they need to see the performance of their servers.
OUT: Bioware

IN: Which person is it?
The government placed a tax on the product so it got more expensive.
OUT: the product

IN: Which person is they?
The ski instructors taught the children the basics of skiing since they are trying to learn.
OUT:
the children