11. Since 1965, the maple tree with red leaves _________ the most well-known Canadian symbol. A. has become B. become C. became D. becoming 12. Canada is made up _________ 10 provinces and 6 territories A. on B. of C. by D. with 13. After the tornado, a great number of people are made __________. A. shaking B. homeless C. raging D. volcanic 14. Up to now, the number of __________ is still an estimate. A. victims B. rescuers C. trapers D. homeless 15. Pollutions are harmful __________ human health. A. with B. at C. to D. on 16. My little sister is afraid of __________, so when there is a bad storm she always hides. A. lightening B. collapsing C. shaking D. scattering 17.The ……… in technology allow astronomers to know more about outer space. A. developments B. science C. exploration D. discovery 18. Sometimes people from different countries can’t understand one another because of ……….. A. body language B. non-verbal language C. language barrier D. verbal language 19. If the etacher were here now, we’d ask him the difference ………. ‘science’ and ‘technology’. A. among B. between C. from D. about 20. Facebook was built on the .............. of earlier social network sites like MySpace and Bebo. A. succeed B. successful C. successfully D. success