1. We should be careful.                                                                                             to

We ought to be careful.

2. I managed to finish all my work.                                                                            able

I was able to finish all my work.

3. I realize that it was a terrible experience for you.                                                  must

It must have been a terrible experience for you.

4. It's against the rules for players to have a drink.                                                    allowed

Players aren’t allowed to have a drink.

5. The best thing for you to do is sit down.                                                                better

You had better sit down.

6. The report must be on my desk tomorrow morning.                                              be

The report has to be on my desk tomorrow morning.

7. It is possible that Joanne did not receive my message.                                          might

Joanne might have not received my message.

8. It's impossible for Martin to be jogging in this weather.                                        be

Martin can’t be jogging in this weather.

9. Tessa wants a cup of coffee.                                                                                   would

Tessa ………. a cup of coffee.

10. It was not necessary for Nancy to clean the flat.                                                  need