Grammar Reference

 

7.1 ■ must, mustn't, have to, don't have to

must and mustn't

Must is used with an infinitive without to. The forms of must are the same for all persons, and there is no auxiliary do in questions or negatives.

Affirmative and negative
I You He / She / It We They	must mustn't (= must not)		wait here.
Questions and short answers
Must	I you he / she / it we they	wait here?	Yes, I must. No, I mustn't.

Note that the question form Must I / you / we, itd. … ? is not very common. Use Do I / you / we have to …? instead. We use must when the speaker feels that it is very important for someone to do something.

I must stop eating chocolate and biscuits.

We must hurry up.

The children must go to bed now.

You must be home before it gets dark.

We use mustn't when it is very important for someone not to do something.

I mustn't be late for the exam tomorrow.

You mustn't take any dictionaries into the exam.

have to and don't have to

Affirmative and negative
I We You They	have to don't have to	study.
He She It	has to doesn't have to
Questions and short answers
Do	I we you they	have to study?	Yes, I do. No, I don't.
Does	he she it		Yes, he does. No, he doesn't.

In affirmative sentences, have to is used in a similar way to must.

You have to be home before it gets dark.

We usually use have to rather than must when the situation (not the speaker) makes the action important.

I have to take two buses to school.(This is the journey to school.)

I have to wear a uniform.(This is in the school rules.)

People have to drive on the left in the UK.(That's the law.)

We use don't have to when it isn't necessary for someone to do something.

You don't have to bring any food. Lunch will be provided.

Note that while the meaning of have to and must is almost the same in the affirmative, the meaning of the negative forms is completely different. Compare:

You mustn't pay John – he hasn't done any work yet.

You don't have to pay John – I have already paid him.

We use the question form Do I / you / we / they have to … ? or Does he / she / it have to … ? to ask if it is necessary to do something.

Do we have to do all the work ourselves?

7.2 ■ Second conditional

We use second conditional clauses to describe present and future situations that are imaginary or unreal. The past forms are used to show the situation is different from reality.

If I met an alien, CONDITION If + past simple,

I'd scream and run away. RESULT would ('d) + infinitive

As with first conditional sentences, the result can come first. In this structure, there is no comma.

I'd scream and run away RESULT would ('d) + infinitive

if I met an alien. CONDITION if + past simple

In the structure if clause + be, the form were can be used with I, he, she and it. We often use If I were you … to give advice to someone. In spoken English, was is more frequent.

If I were you, I'd buy a new phone.

If Lily was / were good at languages, she'd learn Chinese.

We can use negatives in either or both parts of the sentence.

If I won a lot of money, I wouldn't waste it.

I wouldn't eat the food if I didn't like it.

In questions, we can start either with the condition or with the result.

What would you do if you were invisible?

If animals could talk, what would they say?

7.3 ■ I wish …

We use wish + past simple when we want to say that we would like a present situation to be different.

I wish I lived in Paris. (I would like to live in Paris, but I don't.)

We can use were instead of was when the subject of be is I, he, she and it. We don't use would.

I wish Joe were here.

NOT I wish Joe would be here.