Unit 33: MUST AND SHOULD
Must and should are modal verbs. Unit 27 shows you how to make correct sentences with them. This unit shows you when to use them. They have the same kinds of meaning, but must is always stronger than should.
Commands (must only)
You must not leave the store until you pay.
Employees must sign in before beginning their shifts.
Advice or necessity
EXAMPLE: You shouldn't ever argue with a customer.
PRESENT AND FUTURE TIME
Do you think we should rearrange the store display?
Yes, we should; it's in need of a change.
We really must order some new props for the display.
PAST TIME (SHOULD ONLY)
You shouldn't have been rude. It was bad of you.
They should have told him. Why didn't they?
GENERAL (MUST or have got to)
We must take inventory today.
It has got to be finished by tomorrow.
This isn't my receipt. There must be some mistake.
This isn't my receipt. There has got to be some mistake
(I am sure there is a mistake.)
(I can't believe it.)
He should be in his office.
(He is probably there.)
Don't worry. You shouldn't have any problems.
(I don't think you will have problems.)
PAST TIME (MUST ONLY)
I can't see them anywhere. They must have gone home.
(I feel sure that they have gone home.)
I saw them just now. They can't have gone home.
(I feel sure they have not gone home.)
For strong negative probability, use can't (Unit 28).
NOTICE: Ought to (Unit 36) means the same as should.