The dialogues with the correct phrases written in bold are as follows:
Why don't you do some exercise this term? I'm sure you would like it.What do you suggest I am doing/do?Why don;t you take up running?But I haven't got any trainers.You could/may always but a new pair for yourself.They might be expensive. Have you got any other ideas?What about taking/take up hockey?Hockey balls are very hard. When/How about a game with a softer ball.I know!You could go along/to volley ball practice. it's in the gym every Wednesday evening. They have a lot of fun, so I hear. That sounds very tiring/tired. I think I'm staying/I'll stay at home instead.Let's go swimming!he pool is pen today from 2:00 until 4:00.
The bold words are the correct phrases that are to be used.