B1 Grammar
B1 Grammar
Modals - must/can’t deduction
Modals - must/can’t deduction
Use:
The following modals can be used to give recommendations.
must Must can be used to give a strong recommendation.
You must see the Empire State Building while you are in New York.
have to You can also use have to for recommendations, but must is more common. Have to is generally used to talk about rules and things beyond your control.
You have to see the Empire State Building while you are in New York.
should Should and ought to are used to give a suggestion.
You should try haggis while you are in Scotland.
could Could is used to give an option.
You could stay in a hotel, or you could stay at a guest house.
don’t have to Don’t have to is used to say that something isn’t necessary.
You don’t have to get a taxi; the metro is really fast and efficient.
shouldn’t Should is used to warn someone gently against doing something.
You shouldn’t walk home alone after dark.
mustn’t Mustn’t is used to warn someone strongly against doing something.
You mustn’t go to that part of the city – it’s dangerous.
Form:
Must, should and could are modals. Modals follow the following rules.
1) Do not add ‘s’ to the third person singular.
He must. NOT He musts
2) To form a negative, add not after the verb.
I shouldn’t. NOT I don’t should
3) To form questions, invert the modal verb and the subject.
Must you? NOT Do you must?
4) Modals are always followed by a verb in the infinitive form.
I should go. NOT I should to go. / I should coming.
Have to is a regular verb.
1) Use Do / Does / Did to form questions.
Do you have to go? NOT Have you to go?
2) Have to is followed by a verb in the infinitive form.
I have to go.
3) Use don’t / doesn’t / didn’t to form negative sentences.
I don’t have to go. NOT I haven’t to go.
Common Mistakes:
1. Many students use to after modal verbs.
You must to visit the museum. → You must visit the museum.
2. Some students write the question and negative form of have to incorrectly.
You haven’t to take the bus → You don’t have to take the bus.
Have you to go now? → Do you have to go now?