找到下列句子中的错误并改正 (英语题)
1.There's the man who name is Dilbert.
2.I saw dog runnning towards my little sister.
3.Who can take a part of Romeo in the play?
4.Some came by the land,others came by the water,and still others came by the air.
5.There is an one-page newspaper on the table.
6.This math problem is bit difficult for me.
7.He said he had had the cold and couldn't go out.