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 (10) ______ we must do something fast! 1. A. by B. for C. of D. to 2. A. make B. makes C. making D. made 3. A. a B. the C. an D. our 4. A. on B. at C. in D. up 5. A. everything B. all C. every D. some 6. A. warm B. warms C. warmer D. warmest 7. A. are B. be C. is D. being 8. A. near B. to C. in D. on 9. A. so B. then C. but D. if 10. A. but B. however C. and D. or