Answer:
1 It’s easy to hurt your back when you do weights, so don’t try to lift too much.
2 These pictures are really good. When did you start to do photography ?
3 I got a new tent for my birthday, so let’s go camping in the mountains this weekend.
4 Gary doesn’t want to go horse riding again because he fell off last week.
5 When we’re travelling, we often play board games like chess. It’s a great way to pass the time.
Explanation:
I can't explain why these are correct but I can explain why others would be incorrect. You can't "play" photography nor can you "go" photography; Same thing applies to weights. They are acts you perform. While you play chess, because it is a game. You can't "do" camping because the action is based on location; Same as horse riding. I'm not sure how to explain it to make more sense of it.
