Travel by bus is not as popular as ① [it once was] in America. Between 1979 and 1985 alone, the number of passengers declined ② [by about 50 percent]. There are several reasons for this trend. Most of all, large bus companies ③ [have given up] many routes through small-town America. ④ [That's why] they have found it more profitable ⑤ [to concentrate on routes] between  large cities. [      ] 부분중 틀린곳을 찾는 건데요...ㅠㅠ 도저히 모르겠습니다. 해답도 안나와있구요... 답이랑 이유좀 설명해주시면 감사할게요. 학원 다닐 돈이 없어 독학하는데 이 불쌍한 고등학생 좀 도와주세요ㅠㅠ 감사합니다.