Kilo Lingo

Ch 4 · Lesson 15

Must, have to and should

I must go, she has to work, I had to wait, and you should see a doctor: what is necessary, and what is a good idea.

The short version

Must has no past: use had to

.

Not I must work yesterday; had to is the past of must and have to.
Why?

Must and have to both say something is necessary. Must never changes, so it has no past and no future. Have to is an ordinary verb: has to for she, had to for the past, will have to for the future, and do in questions.

Should is advice; must is necessary

.

It is a good idea. You must see a doctor says it is very important.
Why?

Should says it is a good idea, but you can choose. Must and have to are stronger: it is necessary. Shouldn't says it is not a good idea. Like must, should takes no to after it.

Must and have to say something is necessary. Should says it is a good idea. And one pair catches everyone: mustn't means do not do it, but don't have to means you can choose.

necessarya good ideado not do itnot necessary (you choose)What do the colours mean?
MeaningSentence
.
.
.
.
.

How strong is it? From an idea to a must:

An ideaNecessary
  1. You could call her.one idea
  2. You should call her.a good idea
  3. You must call her.necessary

Must and have to: it is necessary

necessarythe part that changesWhat do the colours mean?

Both go before the base verb. After must there is no to; have to keeps its to.

WhoMustHave to
/ / / . .
/ / . .
With he, she and it: has to

Must never changes. Have to is an ordinary verb, so it changes, and it has every tense:

TimeExample
.
.
?
.

Must has no past. For yesterday, use had to: I had to go.

? In everyday speech both say it is necessary, and have to is more common. In British English there is often a small difference:

It comes fromExample
.
.

Should and shouldn't: a good idea

necessarya good ideaWhat do the colours mean?

Should gives advice: it is a good idea, but you can choose. Shouldn't says it is not a good idea.

SituationAdvice
. .
. .
. .
?

Should is softer than must:

  • . (it is a good idea)
  • . (it is very important)

Going further: Mustn't and don't have to and the rest of the guide, when you want them. This lesson does not need them.

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Lesson 15 of 29 in this chapter

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What do the colours mean?