外研版 (2019)必修 第二册Unit 1 Food for thought学案

这是一份外研版 (2019)必修 第二册Unit 1 Food for thought学案，共3页。学案主要包含了情态动词的特征，情态动词的基本用法等内容，欢迎下载使用。
Unit 1 Food for thought情态动词(1)一、情态动词的特征1．情态动词表示说话人对某一动作或状态的态度，有一定的词义，但不能单独作谓语，必须和动词原形，即不带to的不定式连用，才能构成谓语。2．情态动词没有人称和数的变化(have to例外，主语是第三人称单数时，要用has to)。二、情态动词的基本用法1．be able to/can/could[观察例句]①This time I failed，but I'll be able to pass the exam next time.②Mary can speak three foreign languages.③He was able to leave Germany for America during the Second World War.④Tom could sing English songs at the age of 6.⑤What can they be doing there?⑥He can't be in the classroom，for the light has been turned off.⑦It can be quite cold at night here.⑧—Could I use your bike?—Of course you can.[归纳用法](1)表示能力。be able to和can都表示能力，意义上没有区别。但be able to可用于多种时态，而can只有现在式和过去式(could)。[名师点津]was/were able to表示经过一番努力，最后做成了某事；而could表示过去一般的能力。(2)表示推测。can表示推测，常用于疑问句和否定句，有时也可用于肯定句表示理论上的可能性，表示“有时候可能会”。could表示较小的可能性。(3)表示请求和允许。在问句中，could比can语气更委婉。[即学即练1]　选词填空(be able to/can/could)①There's someone outside — who can it be?②However great the difficulties may be，we can overcome them.③The fire was very big，but all the people were able to escape from it.④I can not give you details because I don't actually have any details.⑤Could I have a word with you，if you're not too busy?2．have to/must[观察例句]①Each student has to hand in a composition once a week.②We must do everything step by step.③You don't have to worry about me.I'm a good swimmer.④That car is my property; you mustn't use it without my permission.⑤He must be ill.He looks so pale.⑥If you must go，at least wait until the storm is over.[归纳用法](1)have to意为“不得不”，一般指客观，有时态和数的变化；而must意为“必须；应该”，一般指主观，没有时态和数的变化。(2)have to的否定式意为“不必”，而mustn't表禁止。(3)must表示推测，意为“一定会”，只能用于肯定句。(4)if you must (do sth.)表示虽不赞同但可允许，意为“如果你一定要(那么做)”。[即学即练2]　选词填空(have to/must)①She has to do it herself.She has got no one to help her.②They had/have to put off the sports meet because of the bad weather.③Teachers must be patient enough with their students.④This book must not be removed from the library.⑤If you must smoke，please go outside.3．had better[观察例句]①I think you had better go to the doctor about your cough.②We had better not remain here any longer.[归纳用法]had better do sth.意为“最好做某事”，否定形式为had better not do sth.。[即学即练3]　翻译句子①你明天最好早点来。You had better come early tomorrow.②你最好别错过末班车。You had better not miss the last bus.4．dare/need[观察例句]①You needn't answer my question now.②Need I tell him everything that has happened to his parents?③He dared not tell his parents the truth.④Dare he go home alone at night?⑤He asked me if I dared ride a horse.[归纳用法]need和dare用作情态动词时，主要用于疑问句、否定句和条件从句中，dare有时态变化。另外，need和dare也可用作实义动词。[即学即练4]　完成句子①我喜欢周末，因为不必早起。I love weekends，because I needn't/don't need to get up early．②需要我马上把孩子们召集在一起吗？Need I gather the children together at once?③你怎么敢说我是贼呢？How dare you say I am a thief?④他问我是否敢摸大象。He asked me if I dared touch an elephant．