Complete the gaps with the correct forms of the verbs in brackets. first conditional if life expectancy increases (increase), people will have to (have to) work longer. 1 the air (be) cleaner if we (use) public transport. 2 if unemployment (go) up, i (look) for work abroad. 3 solar panels (not/work) if the sun (not/shine). 4 if we (not/replant) forests, there (be) less oxygen. 5 we (not/be able) to drive if there (not/be) any petrol.