1/ We won't go out unless it stops raining 
--> We won't go out if it doesn't stop raining 
2/ I will call the police unless you give back my bicycle 
--> I will call the police if you don't give back my bicycle 
3/ You wouldn't be able to do this exercise unless your English were good 
--> You wouldn't be able to do this exercise if your English were not good 
4/ Unless we had enough rain, we couldn't grow rice 
--> If we didn't have enough rain, we couldn't grow rice 
5/ The fishermen couldn't have caught a lot of fish unless they had had good nets 
--> The fishermen couldn't have caught a lot of fish if they hadn't had good nets 
6/ I wouln't buy it unless I could afford it 
--> I wouln't buy it if I couldn't afford it 
7/ I would refuse to go unless they paid my expenses 
--> I would refuse to go if they didn't pay my expenses 
8/ I don't agree with his economic policy. I wouldn't vote for him unless he changed it 
--> I don't agree with his economic policy. I wouldn't vote for him if he didn't change it 
9/ He wouldn't have written unless he had heard news 
--> He wouldn't have written if he hadn't heard news 
10/ You might not have a terrible toothache unless you went to the dentist regularly 
Câu này phải bỏ "not" thì mới đúng nghĩa. 
You might have a terrible toothache unless you went to the dentist regularly 
--> You might have a terrible toothache if you didn't go to the dentist regularly