54. A. keep up B. bring up C. put up D. turn up
53. A. international B. interstate C. internet D. interracial
52. A. edge B. decline C. rise D. air
51. A. communications B. marriages C. exchanges D. associations
50. A. difficult B. likely C. important D. risky
48. A. desert B. leave C. escape D. remove
47. A. greater B. stronger C. narrower D. fewer
46. A. mobility B. motive C. moral D. mission
45. A. However B. Moreover C. Therefore D. Furthermore
44. A. force B. influence C. make D. offer