be fed up with - be out of patience with

　　be on one’s own - live independently

　　be on the safe side - take no chances

　　be out of something - have no longer in supply

　　be tired of - be bored with ,frustrated with

　　be up to ones’ears - be extremely busy

　　be up to someone -be a person’s responsibility

　　be out for -trying to get

　　be out of the question - be unacceptable ,impossible

　　bite off more than one can chew - take on more than one can handle

　　break down - cease to function

　　break the ice - begin to be friendly wuth people one doesn’t know

　　break the news - inform or give bad news

　　brush up on - imporve noe’s knowledge of something through study

　　bump into - meet unexpectedly

　　by and large - in general

　　by heart - by memory

　　by all means - absolutely ,definitely

　　by no means - in no way