I play footbal very often. (часто)
I play footbal every week (каждую неделю)
I play footbal very rarely. (редко)
что понравится
The weather is good, isn't it? You don't like ice-cream, do you? Mum cooks tasty, doesn't she?
Его зовут Бося - His name is Bosya
I can play football
I should take this medicine
Children have to do what they are told
You may take...
We should...
I must...
He may (но это не точно)
Can I come in?
Can I help you?
You should...
A fish can...can't...
...But I have to...
...His sister must...
Я не уверен на счет 8 и 15, а вообще в большинство пропусков можно подставлять разные варианты, ибо это по большей части зависит от контекста
1, going
2.to leave
3.drinking
4.to buy
5.working