Complete the text with the correct form of the verbs in brackets. Use the Zero or First Conditional or time clauses.


It’s the largest river in the world. But you 1. (not see) it unless you
2. (climb) the tallest tower in South America or you 3. (fly)
into space. That’s because the river is in the sky over the Amazon. In the rainforest, 1,000 litres of water
go into the air every day from each tree. So when the sun 4. (shine), billions
of tons of water vapour 5. (enter) this river in the sky. When the conditions
6. (be) right, the water vapour 7. (turn into) rain and
8. (fall) on the rainforest soil. If the trees 9. (get) enough
water from the soil, they 10. (send) it back into the air and the cycle continues.
It’s a perfect system. However, if something 11. (happen) to it, the rainforest
12. (die) and that will affect the world.