Grammar › Must, have to and should

Must, have to and should: positive sentences

480 fill-in-the-gap exercises, 48 tests of ten

Must and should take no -s and no to. Have to changes to has to and behaves like an ordinary verb.

Where the obligation comes from

The classic test is who is imposing it:

• I must call my mother. — I have decided; nobody is making me.
• I have to renew my passport. — the rules require it.

Both are correct in most sentences, and Americans use have to in almost all of them. Where the difference shows clearly is in signs and rules, which take must: Passengers must show a ticket.

should for advice

Should does not oblige anyone. It gives an opinion about the best course:

You should take the earlier flight.

Stronger versions exist — ought to means the same thing and is slightly more formal; had better carries a warning: You had better leave now implies something bad happens if you do not.

have got to

In spoken British English, have got to replaces have to:

I*’ve got to** go.*

It has no past form, so had to covers the past for both.

should have

To say what would have been the better choice in the past:

You should have told me. — you did not, and that was a mistake.

All forms

Examples

Taken from the 480 sentences in this drill. The answer is highlighted.

• The system logs every arrival, so employees have to be at work on time.
• Even where nobody is watching, people should follow traffic rules for their safety.
• I am telling you plainly: you must keep this secret!
• The law is plain: he has to be responsible for his own actions.
• The office closes at six sharp, so employees have to complete their daily tasks before leaving.
• Nobody is forcing us, but we should try our best to achieve our goals.
• The school charter binds us: we must be respectful to our teachers.
• His position obliges him, so he has to be careful with his words.
• A patrol checks it at every junction, so you have to wear a seatbelt while driving.
• Nobody is forcing you, but you should eat a balanced diet for good health.
• The traffic here is deadly: he must be careful while crossing the road.
• The company fines latecomers, so he has to arrive on time for the meeting.

Mistakes to avoid

Quick choices from this form

Other forms of Must, have to and should