211.be on duty 值班，值日，在上班时
212.be in duty bound to (do) (=be required by one‘s job or esp. by conscience) 有义务(做)
213.be eager for 想得到，盼望
214.by ear (=play music from memory without having seen it printed) 凭记忆，不看乐谱
215.have an ear for (=have keen recognition of sounds esp. in music and language.) 对……有鉴赏力
216.a word in one‘s ear 私房话，秘密话
217.on earth究竟，到底，全然
218.with ease (=easily) 容易，不费力
219.at (one‘s) ease ( = without worry or nervousness) 自在，不拘束
220.put sb. at his / her ease (=free sb. from worry or nervousness) 使某人感到无拘束
