23. Every day over 1,000 new cars add to the city and the city of over 20 million people is getting more and more . A. expensive B. famous C. difficult D. gridlocked 24. My brother and I often come to school foot. A. at B. in C. by D. on 25. Skycycling tubes will be easy . A. drive B. to drive C. ride D. to ride 26. The white cat is Helen’s, and the black cat is . A. my B. I C. mine D. of mine 27. Driverless cars have already , and they look so cool. A. gone B. travelled C. exist D. existed 28. This is Linda’s hat, and those shoes are . A. her B. hers C. our D. their 29. If I have a jet pack. I will use to fly anywhere easily. A. my B. mine C. his D. their 30. A sky safety system can help cars to traffic jams and crashes. A. prevent B. have C. use D. take 31. I think in the future cities will be more crowded and the traffic will get . A. good B. well C. worse D. worst 32. Remember to the lights before going to bed. A. turn B. turn off C. turn on D. stop 33. Fossil fuels are very common in our society but they the environment. A. renew B. provide C. waste D. pollute 34. What should we do to our electric bills? A. fall B. cut down C. drop D. reduce 35. The digital camera belongs to Nick. That camera is . A. him B. he C. his D. one 36. Is this schoolbag ? A. you B. your C. yours D. them 37. In that country, over 30% of the population live in . A. poor B. poorer C. poverty D. the poor 38. Children who malnutrition can have a lot of diseases. A. suffer from B. avoid C. gain D. obtain 39. There are more problems in the slums than in the areas. A. wealth B. richness C. wealthy D. country 40. Several governments try to the use of fossil fuels. A. reduce B. incr