d) Complete the sentences with the right form of the verb. 1. If we (not stop) global warming, the temperate (rise). 2. Unless we (do) something, we (lose) lots of important towns and cities. 3. We (stop) global warming, when we (stop) polluting the air. 4. If each of us (plant) a tree, he (help) our planet a lot. 5. Polar ice caps (continue) melting, until every human (start) doing something for our planet.

e) Make one sentence out of two using if, when, until, till, etc. The sea level is rising. We need to do anything about global warming. The sea level will rise if we don`t do anything about global warming. 1) The animals are getting extinct. We need to protect them. 2) We need to save fuel. We`re going to run out of it in future. 3) We need to protect our lakes and rivers. They are becoming polluted. 4) We need to stop cutting down rainforests. The hole in the ozone layer is getting bigger. 5) We need to stop global warming. Temperatures are going to rise further.