Parents who smoke often open a window or turn on a fan to clear the air for their children, but experts now have identified a related threat to children's health that isn't as easy to get rid of: third-hand smoke。 That's the term being 1 to describe the invisible yet poisonous mixture of gases and particles(颗粒) clinging(依附) to smokers' hair and 2 , not to mention cushions and carpeting, that stays long after second-hand smoke has cleared from a room. The remaining 3 heavy metals, carcinogens(致癌物) and even radioactive materials that young children can get on their hands and take in, 4 if they're crawling or playing on the floor。 Doctors from MassGeneral Hospital for Children in Boston coined the term 'third-hand smoke' to 5 these chemicals in a new study that 6 on the risks they pose to infants and children. The study was published in the 7 issue of the journal Pediatrics。 'Everyone knows that second-hand smoke is bad, 8 they don't know about this,' said Dr. Jonathan P. Winickoff, the lead author of the study and an assistant professor of pediatrics at Harvard Medical School。 'When their kids are 9 the house, they might smoke. Or they smoke in the car. Or they strap(用带子捆扎) the kid in the car seat in the back and crack the window and 10 , and they think it's okay because the second-hand smoke isn't getting to their 11 . We needed a term to describe these tobacco toxins that aren't 12 .' The study reported on 13 toward smoking in 1,500 households across the United States. It found that the vast majority of both smokers and nonsmokers were 14 that second-hand smoke is harmful to children. Some 95 percent of nonsmokers and 84 percent of smokers 15 with the statement that 'inhaling smoke from a parent's cigarette can 16 the health of infants and children'。 But 17 fewer of those surveyed were aware of the 18 of third-hand smoke. Since the term is so new, the researchers asked people if they agreed with the statement that 'breathing air in a room 19 where people smoked yesterday can harm the health of infants and children'。 Only 65 percent of nonsmokers and 43 percent of smokers agreed with that 20 , which researchers interpreted as acknowledgement of the risks of third-hand smoke。 (    ) 1. A. told                 B. discussed   C. used                 D. mentioned (    ) 2. A. shoes                      B. clothing     C. body                D. mouth (    ) 3. A. includes           B. covers       C. finds                D. improves (    ) 4. A. especially         B. specially    C. immediately      D. regularly (    ) 5. A. name                      B. call           C. explain             D. describe (    ) 6. A. focused            B. tended       C. tried                 D. worked (    ) 7. A. later                 B. latest         C. best                  D. previous (    ) 8. A. but                  B. and           C. however           D. or (    ) 9. A. alongside          B. out of        C. in                    D. beside (    ) 10. A. cough             B. talk           C. observe            D. smoke (    ) 11. A. cars                B. seats          C. kids                 D. windows (    ) 12. A. visible            B. invisible    C. poisonous         D. concrete (    ) 13. A. policies          B. attitudes    C. bans                 D. habits (    ) 14. A. told                B. content      C. confident          D. aware (    ) 15. A. opposed          B. agreed       C. fought              D. connected (    ) 16. A. harm              B. destroy      C. improve           D. confuse (    ) 17. A. quite              B. very          C. far                   D. too (    ) 18. A. chances          B. risks          C. abilities            D. conditions (    ) 19. A. tomorrow       B. today               C. yesterday          D. weekend (    ) 20. A. statement               B. mark         C. discussion         D. prejudice