好问题!对,Get off work 是正式英语,略有下班之意. Knock off 是俚语,作为俚语,knock off 有几个不同意思： 1.下班,休息,或停止.如：Let’s knock off work at noon. 2.完成,做完,草草了事：That author knocked off a book a year early. 3.除掉,减少：She is overweight; she needs to knock off 12 pounds in a month. 4.劫持：The robber knocked off a bank in this neighborhood. 5.复制或模仿：This phone is a knock-off of Apple’s iPhone.
