Modal verbs

Modal verbs are: can, could, be able to, must, have to, should, ought and of course the negative forms of them: can’t , couldn’t, wasn’t/weren’t able to and mustn’t, don’t/doesn’t have to and shouldn’t.

-Use can and could to ask people to do things.

-You use can, could and may to ask for something politely; can and could are more common than may.

-Could is more politely than can. May is formal.

-We usually give permission with can, or we can just say Of course or sure.

Differences between can and could:

Can is kunnen, maar could (zou kunnen) wordt in de volgende gevallen gebruikt:
- om een mogelijkheid te geven 
- bij het maken van suggesties of beleefde verzoeken
- om ergernis aan te geven omwille van iets dat niet is gedaan
- om een sterke neiging om iets te doen aan te geven

When use must, have to and can’t?

-Use must to talk about rules and laws.

E.g: You must stay inside!

-Use the negative form of must (must not or mustn’t ) to talk about things we are not allowed to do. We can also use can’t to talk about things we are not allowed to do (instead of must not or mustn’t).

Have to

-Use have to to talk about rules and laws (similar to must).

E.g: All people have to  carry a ID with them. (This is a law).

-Use don’t have to and doesn’t have to to talk about something which is NOT necessary.

 E.g: A rap doesn’t have to rhyme. (The speaker thinks this is NOT necessary).

-The past of have to is had to.

E.g: I had to hand in the presentation yesterday.

TIP: There are NO past or future forms of must! It also stays the same although the subject change:

E.g: I must leave. He must leave. We must leave. They must leave.

TIP: Please + imperative* is not very polite.

Please + can / could / may + the infinitive without to is polite.

Don’t say Please do it!, say Please can you do it?

TIP: The differences between must, should and have to are:

When you think bij YOURSELF you really have to do something, use must or should. Must is more a law.

E.g: You must go home! | Je moet naar huis!

Should means: zou eigenlijk moeten. It’s more a advice or suggestion.

E.g: You should ask your doctor. | Je zou het eigenlijk je dokter moeten vragen.

You use have to when someone else said that you have to do something and NOT yourself.

E.g: You have to ask it to her.

E.g: Children of a year of 4 have to go to school.

Followed by the infinitive without to:

Can, could, may, must, should, might.

By questions:

Should: Put should before the subject.

*Imperative = Gebiedende wijs