Câu trả lời:
mình chỉ trả lời phần 3 thôi nha tại dài quá 
Use “Unless” instead of if
1.The crops would have been ruined if the flood had risen higher
Unless the flood had risen higher, the crops would not have been ruined
2. If you had not sneezed, he would have known that we were there.
Unless you had sneezed, he would not have known that we were there
3.If she did her hair differently she would look quit nice.
Unless she did her hair differently, she would not look quite nice
4. If John had played for our football team, we would not have lost the game.
Unless John had played for our football team, we would have lost the game.
5.If I won a big prize in a lottery, I’d give up my job
Unless I won a big prize in a lottery, I would not give up my job
6.If you are not careful, you will cut yourself with that knife.
Unless you are careful, you will cut yourself with that knife.
7. If you do not like this one ,I’ll bring you another
Unless you like this one, I will bring you another.
8. I’ll not be able to do any work if I do not have a quiet room.
Unless I have a quiet room, I won't be able to do any work.
9. If she does not hurry, she will be late.
Unless she hurries, she will be late.
10. If we had more rain, our crops would be better.
Unless we had more rain, our crops wouldn't be better.