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)
