If I have enough time, I ... see them in the evening. But I'm not sure because there is a lot of homework to do.

Answer explanation

It's might because the probability is low as it says 'I'm not sure'

Many students in Great Britain ... wear a uniform when they go to school.

Answer explanation

It's an obligation

I'm very tired today. I ... clean my room now, but I'll do it tomorrow.

Answer explanation

It's can't because you are not able to do it today.

I have a bad headache so I ... go to bed earlier.

Answer explanation

It's must because you are talking about something good for you personally.

... I use your phone, please?

Answer explanation

It's can/could because you're asking for permission.

My friend has been coughing a lot recently. I told him that he ... smoke so much.

Answer explanation

It's shouldn't because it is a recommendation.

George has travelled a lot and has lived in different countries. Right now he ... speak four languages: English, Spanish, French and German.

Answer explanation

It's can because it talks about an ability of George.

I'm happy to inform you that I ... come to work next week.

Answer explanation

It's will be able to because it talks about an ability in the future

We ... watch TV tonight. We haven't decided yet.

Answer explanation

It's may/might because it talks about a probability

According to the weather report it ... rain this afternoon.

Answer explanation

It's may/might because it talks about a probability