1. If the tickets weren't expensive, we would visit Hanoi.
2. Unless your son gets up early, he will be late for school.
3. If Tom were here, he could help us.
4. If they were at home today, they would meet their aunt.
5. If Peter didn't drink too much coffee, he could sleep.
6. If they didn't use a lot of wood pulp, many trees wouldn't be cut down.
7. If the weather were nice today, we would go to the zoo.
8. If you press this button, this machine will start.
9. We can only get into the house if someone has a key.
10. Unless we try to reduce world population, it will continue to rise.
11. Unless you keep your feet dry, you will catch a cold.
12. Unless you leave now, we will miss our ride home.
13. Unless you rest, you will be ill.
14. Unless there is water, this tree won't grow.
15. Unless you watch the programme, you can't really guide.
16. Unless you go out in the rain, you won't get wet.