1. You do this when you swim in a pool or in the sea.
When you swim in a pool or in the sea, you go swimming.
Ответ: go swimming
2. This is a long book with a story.
A long book with a story is a book to read.
Ответ: read books
3. You do this when you use a bike for fun or sport.
When you use a bike for fun or sport, you go cycling.
Ответ: go cycling
4. This means to become a member of a club.
Becoming a member of a club means to join it.
Ответ: to join
5. You do this when you show your work to other people.
When you show your work to other people, you present it.
Ответ: to present
6. This means you like something very much.
Liking something very much means to be fond of it.
Ответ: to be fond of