Here are the completed sentences:

1. He uses all his free time to look after his garden.
-> He spends **his free time looking after his garden.**

2. He likes to listen to pop music than to watch TV after school.
-> He prefers **listening to pop music over watching TV after school.**

3. Making crafts or collecting things like stamps and coins are very interesting.
-> It’s **very interesting to make crafts or collect things like stamps and coins.**

4. We usually visit museums when we have leisure time.
-> We enjoy **visiting museums during our leisure time.**

5. A sports car goes faster than an ordinary car. (slowly)
-> An ordinary car goes **slowly.**