A. left B. colleague C. outer D. frightful A. smoking B. steepen C. compete D. rattlesnake A. very B. cough C. food chain D. volcanology A. quality B. atlas C. worry D. commitment A. sorry B. armament C. chewing gum D. stand for A. self-improvement B. touch C. archaeological D. climb a hill A. safety belt B. in a minute C. parking D. ton A. food B. strongly C. sword D. fox A. Chinese knot B. investigate C. hurry up D. cry A. take a walk B. try C. telephone D. healthily