【日常英语口语表达】- have to / must / should

Necessity, Obligation, Lack of Obligation, and Prohibition

We use need to, have to, must, should ,can to show if something is necessary or possible to do.

1. I need to go on a diet. (It's necessary.)
2. Peter doesn't need to work hard now. (It isn't necessary.)


3. You must study hard if you want to pass your exams. (It's necessary, but it's a personal obligation.)
4. You mustn't touch the paintings in the gallery. (It's not allowed. It's forbidden.)


5. You have to wear a seatbelt in a car. (It's necessary, but it's not a personal obligation. It's the law or the custom of the country.)
6. You don't have to help me if you don't want to. (It isn't necessary.)


7. You should see a doctor. (It's a good idea or good advice in a specific situation.)
8. You shouldn't touch the artwork. (It's not a good idea.)



1. In the US, you can turn right at a red light.
2. You can't ride a motorcycle without a helmet.