2. Questions: 1. When did the problem of pollution become dangerous? 2. What problems threaten human lives on the Earth? 3. Why is air pollution harmful? 4. Is it dangerous to breathe polluted air? 5. What does the burning of fuel and fossil fuels produce? 6. What are the most dangerous pollutants? 7. What is the main reason for the greenhouse effect and acid rains on our planet? 8. Can we solve the problem of environmental protection?

1) Would you attack the hijackers if you were on hijacked plane?

2) If they were on a hijacked plane, they would stay calm and would probably survive.

3) If my friend had been trying harder, he would have succeeded.

4) If I had lived in 1703, I shouldn`t (wouldn`t) have had a computer.

5) If she smelt smoke in the middle of the night, she would telephone the fire brigade and run into the street and shout, "Fire!"

6) If he had been invited, he would have come to the party last Sunday.

7) If the driver in front hadn't stopped suddenly, the accident wouldn't have happened.

8) If you don't know how to play, my sister will explain the rules to you.

9) If she had told them it was her birthday, they would have given her a bithday present.

In my opinion, our world in the future will be dangerous. Human's activities on the Earth cause various types of pollution, global warming, greenhouse effect. This can lead to lack of water soon. The ice in Arctic will continue melting and the level of water in seas and oceans will increase.
What about flora and fauna, it can get worse in a couple dozens of years. Some species of plants and animals will probably die because of human.
Political situation is getting worse and worse. In the future, we will certainly have to prepare for global conflicts and wars. 
Also, I think that the population of our planet will increase up to 10 milliards in 50 years, which will make a big amount of problems.

On the other hand, there are some pros too. Cities and towns will continue growing, and new different technologies will be developed. With innovations, we can produce clean water for drinking and watering plants. People will be smarter, because of improving of education.
And, maybe, Mars will be colonised. It will open some new directions for us.