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

　　71. begin with以…開始to begin with(=first of all)首先，第一(經(jīng)常用于開始語)

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

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

　　74. benefit(from)受益，得到好處

　　75. for the benefit of為了…的利益(好處)

　　76. for the better好轉

　　77. get the better of(=defeat sb.)打敗，勝過

　　78. by birth在出生上，論出身，按血統(tǒng)at birth在出生時;give birth to出生

　　79. blame sb. for sth.因…責備某人blame sth. on sb.把…推在某人身上

　　80. in blossom開花(指樹木)be in blossom開花(強調狀態(tài))come into blossom開花(強調動作)

　　81. on board到船上，在船上，上火車或飛機

　　82. boast of(or about)吹噓

　　83. out of breath喘不過氣來

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

　　85. in bulk成批地，不散裝的

　　86. take the floor起立發(fā)言

　　87. on business出差辦事

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

　　89. last but one倒數(shù)第二

　　90. but for(=without)要不是表示假設