Should/shouldn 't

When should or shouldn't refer to desirability, obligation or

likelihood, they remain unchanged in indirect speech:

'You should see a specialist,' he told me

He told me I should see a specialist.

Should used in place of would, e.g. in conditional sentences [>

14.2. 14.11n1], becomes would [compare shall above]:

'If I were you, I should get another lawyer'

She said (that) if she were me, she would get another lawyer

Would, could, might, ought to, needn't have, used to

These (including negative forms where applicable) remain unchanged in indirect speech in all combinations:

15 Direct and indirect speech

'/ would like an appointment tomorrow, I said to my dentist I told my dentist (that) I would like an appointment the next day 'You ought to slow down a bit, the doctor told him The doctor told him (that) he ought to slow down a bit

'perfect' and 'past' modal forms [> 11.8.4]

Forms such as must have and could have remain unchanged:

7 must have slept through the alarm ' she said

She said she must have slept through the alarm

Must

When referring to the past, must can remain unchanged in indirect speech when it is used to indicate inescapable obligation. Or we can use had to (the past of have to) in its place: / must warn you of the consequences,' he said He told me he must/had to warn me of the consequences

Must, indicating future necessity, can remain unchanged, or can be

replaced by would have to or sometimes had to:

'We must go early tomorrow ' she said

She said they must go early the next day (or She said they would

have to go/they had to go)

When must is used to indicate deduction or possibility, it remains unchanged in indirect speech. It cannot be replaced by had to: 'George must be a fool to behave like that' he said He said George must be a fool to behave like that

Mustn't (prohibition) remains unchanged or changes to couldn't: 'You mustn't/can't cross the border,' the guard said The guard said we mustn't/couldn't cross the border