unit3When和while引导的时间状语从句.ppt

Unit3 What were you doing when the UFO arrived?,八道沟镇中学 赵媛霖,过去进行时的概念及构成,构成：主语+was/were+doing sth+时间状语,概念：表示过去某一时刻或某段时间正在进行的动作,指示词：then、 at that time、once等连用，或者用另一动作来表示过去的时间。,1、延续性动词与非延续性动词,延续性动词指动作可以延续一段时间，而不是瞬间结束。,如：work study drink eat 等,非延续性动词指动作极为短暂，瞬间结束。,如：start begin hit jump knock等,When与while引导的时间状语从句,When表示”当时候”。从句中既可以用延续性动词，又可以用非延续性动词，这些动词既可以表示动作，又可以表示状态。从句中的动作既可和主句动作同时发生，又可在主句动作之前或之后发生。,如：Mary was having dinner when I saw her. The boy was still sleeping when his mother got home yesterday evening.,When与while引导的时间状语从句,While表示“在时候”、“在期间”。它强调主句的动作与从句的动作同时发生，或主句的动作发生在从句的动作过程中。While从句必须是表示动作或状态的延续性动词。如： The weather was fine while we were in Beijing. She called while I was out. 如果主句的动作在从句的动作过程中发生，从句常用进行时，如： While we were swimming someone stole our clothes Dont talk so lould while others are working.,Summary,1.When可指时间点，又可指时间段，从句中可用延续性动词，也可用非延续性动词。 2.While总是指一个时间段，从句中必须用延续性动词。 3.统一时态：主句过去式，从句也是过去式。,Exercises: fill with “while” or “when”,May was talking on the phone,her sister walked in Rita bought her new dog,it was wearing a little coat. I saw Carlos , he was singing louldly. I was dancing , he was singing louldly. Linda finally saw David, he was jumping with a dog. I was cleaning my room the fire broke out,While,While,When,When,When,When,Exercises,7. I was walking in the street the accident happened. 8. you have a meeting, you should turn off your mobile phone. you have PE class, you should wear sports shoes. I was doing my homework, the phone rang. it was raining, the plane took off. the teacher was speaking to class, he stood up suddenly.,when,When,When,While,While,While,谢谢观赏,What are dreams? Dr