Read the article. choose the best word (a, b or c) for each space. the world is getting hotter the world is getting hotter because 1) ………. us! our factories, cars, trains and planes 2) ………. the air dirty. when 3) sun shines, everything gets hot and the dirt stops the hot air from going 4) ………. to the sky. because the hot air has nowhere to go, 5) ………. gets hotter. already our world is 6) ………. than it was one hundred years ago. hot countries may become drier and the people who live there will not be able to grow enough food. ice in cold areas 7) ………. changing to water because of higher temperatures. when this happens, the seas become bigger. some towns 8) ………. the sea may have a problem soon. we can help 9) ………. we stop making the air dirty but we 10) ………. do something fast! 1) a. by b. for c. of 2) a. make b. making c. makes 3) a. a b. the c. an 4) a. on b. at c. up 5) a. everything b. all c. every 6) a. warm b. warmer c. warmest 7) a. are b. be c. is 8) a. near b. to c. in 9) a. so b. if c. but 10) a. must b. should c. can