Find and correct the mistake in each sentence.

1. My mum and my dad was playing in the sand with my sister.
2. You not have to go if you don't want to.
3. We mustn't run. The train doesn't go for an hour.
4. You must to be careful. It's very dangerous.
5. I played football when I broke mu leg.
6. Yesterday the sports shop was sell them for only £15.​