61. on the average (=on average, on an average) 平均
62. (be) aware of (=be conscious of , having knowledge or consciousness)意識到,知道.
63. at the back of (=behind) 在…后面
64. in the back of 在…后部(里面); on the back of 在…后部(外面); be on one’s back(=be ill in bed) 臥病不起.
65. at one’s back(=supporting or favoring sb.) 支持,維護; have sb. at one’s back 有…支持, 有…作后臺

66. turn one’s back on sb. (=turn away from sb. in an impolite way) 不理睬(某人),背棄,拋棄
67. behind one’s back 背著某人(說壞話)
68. be based on / upon 基于
69. on the basis of 根據(jù)…, 在…基礎上
70. beat…at 在…運動項目上打贏