up to the average达到一般水平
be aware of知道，意识到，认识到
right away立即，马上，立刻
be at the back of sb.支持某人
behind sb's back暗中
put one's back into sth.专心致志于某事
be back回来
back and forth来回，往返，来来往往地
keep one's balance保持平衡，保持冷静
lose one's balance失去平衡，跌倒
base oneself on根据，基于
be based on以...为基础，以...为根据
bear away夺得;赢得(奖品等)
bear off赢得;使离开;驶离
bear down竭尽全力;(on)压倒，击败
bear upon对……施加压力，有关，瞄准
bear up支持，拥护;打起精神
bear with宽容;耐心等待
beat about四处闲逛，[航海]迎风斜驶
beat down(太阳等)强烈地照射下来;打倒，平息
