back and forth 来回地，反复地
back of 在……后面
back up 后备，支援
bare of 几乎没有，缺乏
be able to do 能够
be around 差不多
be available to sb. 可用，可供
be bound to 一定
be capable of doing 能够
be concerned with 关心…，涉足…
be dying to 渴望
be fed up with 受够了be tired of
be in hospital 住院
be in season 上市的/in peak season 旺季
be in the mood to do sth. 想做
be pressed for time 时间不够
be tied up with 忙于
be under the weather 身体不好
beat around the bush 拐弯没角
beat the crowd 避开人群
before long 不久以后
behind schedule 误点
bent on sth. 下定决心做…
beside point 离题的，不相干的
beyond one's ability 超越某人的能力
beyond question 毫无疑问
book on reserve 须留的图书
booked up 订完了
bound for开往
break down 抛锚
break though 突破
break up with 和某人分手 be through with / be finished with
bring about 使…发生
bring someone up to date 帮某人赶上 help someone catch up
by accident 偶然
by air 通过航空途径
by all means 尽一切办法，务必
by and by 不久，迟早
by chance 偶然，碰巧
by far 最，……得多