Helen fell off her horse last week but luckily she managed to /could get back on and ride home.
managed to
There can/ may be water on the moon's surface.
may
If the weather's bad tomorrow, the race could/ might not go ahead.
might
My present from Alice didn't come in the post, so she must be / is delivering it by hand.
must be
We'd better leave soon. It's Friday evening and there should / will be a lot of traffic.
will
Lewis must / should have been training very hard to develop muscles like that!
must
Do you know if we must / have to have visas for South Africa?
have to
What a state my football shirt is in! It needs / must be washing.
needs
There wasn't anyone at the main gate so we didn't need to show / needn't have shown our tickets.
didn't need to show
We have to / are supposed to put our bags in the lockers, but most people take them into the gym.
are supposed to
Polite notice: children do not have to / are not allowed to play on the grass.
are not allowed to
The newspaper shouldn't / mustn't have printed the rumour without evidence.
shouldn't
I wonder where Dad is." "He is / will be driving to the airport, I should think.'
will be
Dad always helped us out / would always help us out financially when we were at university, however difficult it was for him.
both are correct
Hang on a minute - can / might you repeat what you just said?
can
