【本单元例句呈现】
(1) The boy was walking down the street when the UFO landed? 当UFO落地时男孩正沿着街走。 (2) While the boy was walking down the street, the UFO landed. 当男孩正沿着街走时, UFO落地了。 (3) The girl was shopping when the alien got out. 当外星人出来时这个女孩在买东西。 (4) While the girl was shopping, the alien got out. 当这个女孩在买东西时，外星人出来了。 【概念讲解】 以上四句是由when与while引导的时间状语从句。这四句中还包含了一个很重要的时态：过去进行时。 1. 构成：过去进行时由 “was / were +动词-ing”构成 2. 意义： (1) 表示在过去某一时刻或某一段时间正在进行的动作。这一特定的过去时间除有上下文暗示以外，一般用时间状语来表示。如： — What was he doing when the UFO arrived? 当UFO落地时他正在干什么？ — He was sleeping late when it arrived. 当UFO落地时她正在熟睡。 Many people remember what they were doing on April 4, 1968. 许多人记得在1968年4月4日他们正在做什么。 (2) 表示过去某一动作发生时另一动作正在进行。一个长动作发生的时候，另一个短动作也发生。 3. 标志词： (1) at 9 o'clock yesterday, from 8 to 9 yesterday morning, at this / that time yesterday, this morning, the whole morning, all day yesterday, when, while, 如： We were having an English class at 9 o'clock yesterday. 昨天9点我们正在上英语课。 Xiao Ming was sleeping all day yesterday. 昨天一整天小明都在睡觉。 (2) 主句（过去进行时）＋ when + 从句（一般过去时） (3) 主句（一般过去时）+ while +从句（过去进行时） The girl was shopping when her friend saw her. 当她的朋友看见她时女孩在买东西。 The dog got out of the box and ran away while Linda was buying the newspaper at the station. 当Linda 在车站外买报纸时，狗从箱子里出来逃跑了。 4. 过去进行时的各种句式： 下面以动词work 为例，将过去进行时的肯定式、否定式和疑问式以及简略答语归纳如下： 肯定式：I / He / She / It was working. We / You / They were working. 否定式：I / He / She / It was not working. We / You / They were not working. 疑问式和简略回答： — Was I working? — Yes, you were. / No, you were not. — Were you working? — Yes, I was. / No, I was not. — Was he / she / it working? — Yes, he / she / it was. / No, he / she / it was not. — Were you / they working? — Yes, you / we / they were. / No, you / we / they were not. 注：was not常缩略为wasn't; were not常缩略为weren't. 5. 比较： (1) 一般过去时与过去进行时用法比较： ■一般过去时表示在过去某个时间发生过的动作或存在的状态，而过去进行时则表示在过去某一时刻或某一时间正在进行的动作。如： David wrote a letter to his friend last night. 大卫昨晚给他的朋友写了信。（信写完了） David was writing a letter to his friend at 8 last night. 昨晚8点大卫一直在给他的朋友写信。（信不一定写完） ■表示过去将来，多用于go, come, leave, start, take off等动词。如： He said he was leaving for home in a day or two. 他说他一两天之内就动身回家了。 ■表示过去的经常动作，常与always, forever等连用，略带感情色彩。如： She was always thinking of others. 她老是想到别人。（赞扬） She was forever complaining. 她老是抱怨。（厌烦） （2）when 与while区别 ■when表示“当……的时候”。从句中既可用延续性动词，又可用非延续性动词，这些动词既可以表示动作，又可表示状态，常跟一般过去时。 When the UFO took off, the boy was taking photos. 当 UFO起飞时，男孩在照相。 Mary was having dinner when I saw her. 当我看见她时玛丽吃午饭。 The boy was still sleeping when his mother got home yesterday morning. 昨天早上当她的母亲到家时男孩仍然在睡觉。 ■While表示“在……的时候”“在……期间”。while从句中必须是表示动作或状态的延续性动词，常跟过去进行时。Tag:八年级英语教学设计，八年级英语教学设计方案，教学设计 - 英语教学设计 - 八年级英语教学设计