Unit1 Science and Scientists Sentence pattern--高中英语人教版（2019）选择性必修第二册.pptx

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1、Unit1 Science and Scientists SENTENCE PATTERNlearning aims:1)To learn these sentences pattern usage:once引导时间状语从句引导时间状语从句/until引导时间状语从句引导时间状语从句/seem相关句型相关句型2)To use these sentences pattern correctly.Think and study independently(3)Look at the content about“once引导时间状语从句引导时间状语从句/until引导时间状引导时间状语从句语从句/s

2、eem相关句型相关句型”on p (),underline some difficulties with red pen.Self-learning guidance:(6)1)To summarize the language points p Task .2)To finish some exercises.3)To check the answers.1.once引引导时间导时间状状语语从句从句.作连词时表示“一旦;一经”,引导时间状语从句。如果主句用一般将来时，则once引导的时间状语从句常用一般现在时表将来，即“主将从现”。e.g.Once you get into a bad ha

3、bit,you ll find it hard to get out of it.一旦染上坏习惯，你会发现想改掉就难了。2.until 引引导时间导时间状状语语从句从句 until可以作为介词,后接一个表时间点的名词(短语)，也可以作为连词,引导时间状语从句。其否定形式是not.until.意为“直到.才.”He didnt start to do his homework until his father came back.直到他父亲回来他才开始做作业。It was not until his father came back that he started to do his homew

4、ork.直到他父亲回来他才开始做作业。(not.until.的强调句)Not until his father came back did he start to do his homework.直到他父亲回来他才开始做作业。(not.until.的倒装句)知知识识拓展拓展:状状语语从句的省略从句的省略状语从句中，若从句的主语是it或与主句的主语相同(或者从句的主语为it)，且谓语动词中含有be动词时，可将从句的主语和be动词一起省略。省略后的结构为:连词+现在分词/过去分词/介词短语/adj./n.。While(he was)wandering around the supermarket

5、yesterday，he came across an old friend.昨天在超市闲逛的时候，他遇到了一位老朋友。When(he was)asked about the question,he said nothing.被问到这个问题时，他什么都没有说。AnswersTask Self-learning guidance:(6)1)To summarize the language points p Task .2)To finish some exercises.3)To check the answers.3.seem 相关句型相关句型seem 为连系动词，意为“似乎;好像”,用来表

6、示说话人内心有一定依据的判断或猜想。(1)seem可接动词不定式(短语)，使用时应注意不定式(短语)的形式变化:一般式 to do(不定式动作发生在谓语动作之后);进行式to be doing(不定式动作与谓语动作同时发生);完成式to have done(不定式动作发生在谓语动作之前)。You seem to have ceaught a cold.看来你已经感冒了。(感冒在seem之前已经发生)You seem to catch a cold.看来你要感冒了。(感冒发生在seem之后)He seems to be doing his homework.他好像正在做作业。(做作业与seem同

7、时发生)(2)seem的相关句型seem to be+adj./n./介词短语/分词,其中to be可省略e.g The man over there seems to be a new teacher.那边的那位男士看起来好像是一个新老师。seem like+n.看起来像It seems that.似乎/好像.(从句用陈述语序)e.g It seems that no one knows what has happened in the park.似乎没有人知道公园里发生了什么事。It seems as if/though.好像.(从句常用虚拟语气)e.g It seemed as if t

8、hey would get married in the end.好像他们终于要结婚了。There seems to be.好像/似乎有.e.g There sems to be a lot of support for this move.似乎有很多人支持这项举措。AnswersTask Summary(语言总结语言总结)本节课学习了“once引导时间状语从句引导时间状语从句/until引导时间状语从句引导时间状语从句/seem相关句型相关句型”的相关短语，利用小循环进行操练，以下为知识点总结(1)seem可接动词不定式(短语)，使用时应注意不定式(短语)的形式变化:一般式 to do(不定式动作发生在谓语动作之后);进行式to be doing(不定式动作与谓语动作同时发生);完成式to have done(不定式动作发生在谓语动作之前)。