Trees not only bring nature to urban areas, but they also help clean the air by absorbing pollutants, ____ oxygen, ____ water, and grow food. A. providing - saving B. provide - save C. to provide - to save D. to provide - save Sometimes it’s better not to buy something new, and buy it ____ instead. A. used b. useable c.use d useful 2.Air pollution is such a serious_____ that it has been a direct factor in the of millions of people each year. A. threaten - deaths B. threaten - death C. threat - death D. threat - deaths giups e voi a . E cam on