47. will understand - practise
48. will do
49. need
50. won't be
Exercise 2:
1. If we plant more trees, the air will be fresher.
2. If we use fewer cars, we will reduce pollution.
3.If we cycle to school every day, we will keep fitter.
4. If we use recycled products, we will safe money.
5. If people throw rubbish into the right bin, they will keep the evironment clean.
6. If we turn off the tap when brushing the teeth, we will safe a lot of water.
7. If people travel more by public transport, the harmful gases in big cities will be reduced.
8. If we start at six, we will arrive there before noon.
9. If the boy eats so many green apples, he will be ill.
10. If we use reusable bags for shopping, we will reduce waste.