英文语法介词!填充!

英文语法介词!填充!
1 - She wasn't short,she wasn't tall; she was ___________ average
height.
2 - What are you going to buy Hania ___________ her birthday?
3 - The police are looking ___________ a tall,black man who was
seen standing outside the bank just before the robbery took place.
4 - The teacher asked the class to do the exercise ____________ the
bottom of page 12.