3 Complete the gaps with the correct forms of the verbs in brackets.

If life expectancy increases (increase), people will have to (have to) work longer.

1 The air will be cleaner if we use public transport.

2 If unemployment goes up, I will look for work abroad.

3 Solar panels will not work) if the sun does not shine.

4 If we do not replant forests, there will be less oxygen.

5 We shall not be able to drive if there is no any petrol.