用who,whom或which把以下每对句子改写成一句话.

问题描述:

用who,whom或which把以下每对句子改写成一句话.
1.This is the ticket.I bought it yesterday.
2.The girl is standing beside the window. She is a new student.
3.There are the presents. I bought them for my parents.
4.The car is expensive. He can't afford it.

1.This is the ticket which I bought yesterday.
2.The girl who is standing beside the window is a new student.
3.There are the presents which I bought for my parents.
4.The car which he can't afford is expensive.