1. if i don't finish my homework in an hour, i'll be late for the party
2. if i leave home late, i'll miss the bus
3. if i miss the bus, i'll walk to the town centre
4. if i walk to the town centre, i won't get to the cinema at 7 o'clock
5. if i don't get to the cinema at 7 o'clock, i won't be able to sit next to my friends