at present 目前；现在
at sb's disposal 任……处理
at the cost of 以……为代价
at the mercy of 任凭……摆布
at the moment 此刻；目前
at this rate 照此速度
at times 有时；间或
back and forth 来回地；反复地
back of 在……后面
before long 不久以后
beside point 离题的，不相干的
beyond question 毫无疑问
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
by hand 用手，用体力
by itself 自动地,独自地
by means of 用，依靠
by mistake 错误地；无意地
by no means 决不；并没有
by oneself 单独地；独自地
by reason of 由于
by the way 顺便说说
by virtue of 借助，由于