小学常见介词：1.on(1) 在-上面 The book is on the desk.(2) 在-（哪一天/星期）What do you do on Wednesday?(3) 在-（月、日）My birthday is on August 2nd.2. in（1）在-里面 The pens are in the pencil-box.(2)在-（哪一年/月）His birthday is in October.He worked here in 1992.(3 ) 在-（地方） He works in Dongguan.(4 ) 在-之内 What are you going to do in 20 years?(5 ) 在-（早上、下午、晚上）I do morning exercises in the morning every day.I usually play basketball in the afternoon.I often do my homew
