2.Plant more trees or the air will be seriously polluted. • If we plant more trees, the air will be seriously polluted. • we don’t plant more trees if the air will be seriously polluted. • If we don’t plant more trees, the air will be seriously polluted. 5.Many people speak English in the world. • English spoken all over the world by many people • English is spoken all over the world by many people • People of all over the world speak English 7.Emma came first because she worked hard. • A.Emma came first due to she worked hard • B.Emma came first as a result of her hard work. • C.Emma came first because she worked hard 8.All flights had to be cancelled as a result of the pilots' sudden strike. • A.The pilots suddenly went on strike, so all flights had to be cancelled. • B. Because the pilots suddenly went on strike, so all flights had to be cancelled • C. All flights had to be cancelled because of the pilots suddenly went on strike 9.If I could swim, I would go scuba diving with Terry. • Because I can swim, I won't go scuba diving with Terry. • Because I can swim, I will go scuba diving with Terry • C.Because I can't swim,I won't go scuba diving with Terry. 10.The factory dumps its waste into the river, so the water is seriously polluted. • If the factory didn’t dump its waste into the river, the water wouldn’t be seriously polluted. • If the factory dump its waste into the river, the water wouldn’t be seriously polluted • If the factory didn’t dump its waste into the river, the water won’t be seriously polluted 11. Before the typhoon hit the area, the old had been evacuated to safe places. • Before the typhoon hit the area, the old evacuated to safe places. • B.After the old had been evacuated to safe places, the typhoon hit the area. • After the old had been evacuated to safe places, the typhoon hits the area. 12. Polluted air has led to the local people’s breathing problems. • Polluted air has led the local people’s breathing problems. • Polluted air has caused to the local people’s breathing problems. • Polluted air has resulted in the local people’s breathing problems. 13. The factory has treated all the chemical waste well. • All the chemical waste has been treated well by the factory • The factory has been treated all the chemical waste well. • All the chemical waste was treated well by the factory 14. Although people prepared carefully for the storm, they suffered severe damage. • Despite people’s careful preparation for the storm, they suffered severe damage. • B.Despite the fact that people prepared carefully for the storm, they suffer severe damage. • Despite people prepared carefully for the storm, they suffered severed damage.