I think she was wrong to make a promise she couldn't keep // She ... a promise she couldn't keep. (NOT)
shouldn't have made
Sarah left work. I think she can be feeling / may be feeling a bit sick.
may be feeling
A: 'But it was an accident!' B: 'Well, you should / would have been more careful.'
should
I overslept, but I could / was able to catch my flight on time!
was able to
I didn't have time to practise before the music performance. // I ... practise before the music performance. (WAS)
wasn't able to
You're tired. You could / must have had a bad night's sleep.
must
You must have made / must make more of an effort in class.
must make
You mustn't be standing / mustn't stand on the desk. Otherwise, you'll break it.
mustn't stand
A: 'Where is Emma?' B: 'She might be playing / might play outside.'
might be playing
I bought a ticket but it wasn't necessary - I made a mistake. // I ... a ticket. (NOT)
needn't have bought / didn't need to buy/ shouldn't have bought
It was a mistake for you to buy a dog. You ... a dog. (NOT)
shouldn't have bought
A: 'It's taking Billy a long time to get here...' B: 'I think he might have taken / might be taking the bus.'
BOTH
I told you this would happen. You should listen / have listened to me in the first place!
should have listened
Why did I bother buying a big bottle of water? Samuel had already packed one. I didn't need to bother / shouldn't have bothered.
shouldn't have bothered
You mustn't / needn't look at other students' work. It's against the rules.
mustn't
My boss missed the meeting today. She can't have / mustn't have been told.
mustn't have
I can't find Lucy anywhere. Do you think she could / must have gone home?
could have
Were you able to / Could you do some grocery shopping before you arrived home today?
Were you able to
When I was young, I was able to / could touch my toes easily.
could
You gave the tour guide a tip but it was not necessary. // You ... give the tour guide a tip. (NOT)
didn't need to
A: 'Why did you worry when I went bungee jumping?' B: 'You ... injured'. (GOT)
could have got
I didn't see the cats fighting last night, but I sure could / was able to hear them!
could
I needn't have worn / didn't have to wear a hat to the ceremony, but I did because I had just bought a new one.
BOTH
I think her book would / should have sold millions but the publishers thought it wasn't enough.
would
We didn't dress up smartly because it wasn't necessary. It was a casual party. // We ... dress up smartly because it was a casual party. (NOT)
didn't need to
I worked fast and finished my essay on time but now the teacher has given the class 2 more weeks. // I ... so hard. (NEED)
needn't have worked
You should buy / have bought a better telescope with the money you'll get on your birthday. This one isn't very good.
buy
Eva shouldn't have / didn't need to put on a party two days before New Year's Eve. Almost no one came.
shouldn't have
A: 'Did you know the smallest whale is only 2cm?' B: 'That couldn't / can't be true!'
can't
It was wrong of them to use the machine without asking for permission first. // They ... permission before using the machine. (ASK)
should have asked for