Read the text below and choose the best answer to the following questions. Air pollution is mainly caused by the burning of fossil fuels, which releases particles, gases and chemicals (1)__________ the air. Common pollutants in London include carbon monoxide, carbon dioxide, sulfur dioxide, nitrogen oxide and methane. Fossil fuel-powered transportation, power generation and manufacturing processes (2)__________ air pollution. Open waste burning, residential cooking and heating, and slash-and-burn agriculture also contribute to urban air pollution in London, according to a recent study of the world's megacities. Air pollution affects both people (3)__________ environment around the world. It causes stroke, heart disease, lung cancer, and chronic and acute respiratory diseases, including asthma. The World Health Organization reports that each year 7 million people die prematurely – or one in every nine deaths – are linked to health effects related to indoor and outdoor air pollution. (4)__________ , studies show that air pollution also contributes to climate change; reducing air pollution in London would help slow the effects of global warming. 1, a, into b, to c, with d, in 2, a, cause b, affect c, lead in d, result to 3, a, the b, a c, an d, that 4, a, Moreover b, However c, Otherwise d, Therefore