人教新目标英语八下 Unit 5 单元语法知识梳理

这是一份人教新目标英语八下 Unit 5 单元语法知识梳理，共3页。
一、过去进行时态1.概念：过去进行时表示在过去某一时刻或某一段时间内正在进行的动作。这一特定的过去时间，除了有上下文暗示以外，一般带有具体的过去时间，如：this time yesterday，at 9：00 yesterday morning等；或以when，while 引导的时间状语来表示。2.构成：过去进行时的基本结构为：主语 + was/were + v.ing + 其它成分。否定形式是在be后加not；一般疑问句是将be提前。下面以work为例，将其肯定式，否定式和疑问式及简略答语表述如下肯定式与否定式：I/He/She/It was working. I/He/She/It was not working.We/You/They were working. We/You/They were not working.疑问式与简略答语：—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/we/they working?—Yes，we/you/they were./No，we/you/they were not. was not常缩写为wasn't； were not常缩写为weren't。过去进行时与一般过去时的用法区别：过去进行时表示过去正在进行或发生的动作，强调动作的持续性，动作可能尚未完成；而一般过去时则多强调动作的发生或已完成。例句：Mary was writing a letter to her father last night.玛丽昨晚一直在给她爸爸写信。（强调写信过程的延续性，但信不一定写完了。）Mary wrote a letter to her father last night.玛丽昨晚给她父亲写了封信。（强调“写信”这个动作，信已经写完了。）二、when 和 while 用法小结when 和while 都可以作从属连词，引导时间状语从句，都有“当……的时候”的意思。但用法有别：1.when 引导的时间状语从句既可以指时间段，也可以指时间点，从句中谓语动词既可以是延续性动词，也可以是终止性动词；但while引导的时间状语从句则一般指一段时间，含义是during the time，偏重于动作的过程，从句谓语动词为表状态的延续性动词。例句：It was raining when they arrived. 当他们到达时，正在下雨。（某一时间点）My wallet dropped on the ground when I was walking in the park.我在公园散步时，钱包掉在地上了。（一段时间）Tom fell asleep while his math teacher was giving a lesson.汤姆在数学老师上课的时候睡着了。（接时间段）2.由when引导的时间状语从句中，从句的动作和主句的动作可以同时发生，也可以一前一后先后发生；但while则强调主句和从句的动作同时发生。所以，有时when可以代替while，而while则不能代替when。例句：When they heard the good news，they jumped with joy.当他们听到这个消息时，高兴得跳了起来。（while不能代替when）3.when后面通常接一般过去时的从句，而while后接进行时态的句子。例句：While the girl was shopping，the alien got out.= When the alien got out，the girl was shopping.正当那个女孩买东西时，外星人出来了。