61. on the average (=on average, on an average) 平均

　　62. (be) aware of (=be conscious of , having knowledge or consciousness)意识到,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) 卧病不起.

　　65. at one's back(=supporting or favoring sb.) 支持,维护; have sb. at one's back 有…支持, 有…作后台

　　66. turn one's back on sb. (=turn away from sb. in an impolite way) 不理睬(某人),背弃,抛弃

　　67. behind one's back 背着某人(说坏话)

　　68. be based on upon 基于

　　69. on the basis of 根据…, 在…基础上

　　70. beat…at 在…运动项目上打赢

　　71. begin with 以…开始. to begin with (=first of all) 首先, 第一(经常用于开始语)

　　72. on behalf of (=as the representative of) 以…名义

　　73. believe in(=have faith or trust in; consider sth.sb. to be true) 相信,依赖,信仰.

　　74. benefit (from) 受益,得到好处.

　　75. for the benefit of 为了…的利益(好处)

　　76. for the better 好转

　　77. get the better of (=defeat sb.) 打败, 胜过.

　　78. by birth 在出生上,论出身,按血统 at birth 在出生时; give birth to 出生

　　79. blame sb. for sth. 因…责备某人 . blame sth. on sb. 把…推在某人身上

　　80. in blossom开花(指树木) be in blossom开花(强调状态) come into blossom开花(强调动作)

　　81. on board 到船上, 在船上, 上火车或飞机

　　82. boast of (or about) 吹嘘

　　83. out of breath 喘不过气来

　　84. in brief(=in as few words as possible)简言之

　　85. in bulk 成批地,不散装的

　　86. take the floor 起立发言

　　87. on business 出差办事.

　　88. be busy with sth.于某事 。 be busy doing sth. 忙于做某事

　　89. last but one 倒数第二.

　　90. but for (=without) 要不是. 表示假设