概要：: You must do your homework. You should speak to your parents politely.. I ought to write to him today. 2.must 与have to must表示"必须",侧重于说话人的主观意志。 have to 表示"必须", 侧重于客观的需要,含有"不得不"的意味 。 3.had better (常缩写为'd better) ,是一固定词组, 表示"最好", 用于表示对别人的劝告、建议或表示一种愿望。 had better 后面加动词原形,即 had better do sth.不论主语是第几人称, 句子无论是何种时态,had better 形式不变。had better 的否定形式为had better not do sth 表示"最好不要做……"。如:You'd better not miss the last bus. You'd better not play on the road. It's dangerous. You'd better put on the coat. It's cold outside. 4.Why not…?/Why don't you …? 这两种句型结构常用于说话人向对方提出一个建议,意思是&q

九年级英语9AUnit5 Grammar学案,http://www.ketang123.com

九年级英语9AUnit5 Grammar学案

    1.should 和ought to 与must区别
    用should/ought to 可以表示"劝说"或"督促", 和must 一样, 但三者语气强弱不同。
    用should 语气比较肯定一些, 说话人的主观信心要强烈一些。含有责任的意思。
    用ought to则口气上不那么坚定。
    用must则在口气上最强烈,含有责任的意思。例如:
    You must do your homework.  You should speak to your parents politely..
    I ought to write to him today.
    2.must 与have to 
    must表示"必须",侧重于说话人的主观意志。
    have to 表示"必须", 侧重于客观的需要,含有"不得不"的意味 。
    3.had  better (常缩写为'd better) ,是一固定词组, 表示"最好", 用于表示对别人的劝告、建议或表示一种愿望。
    had better 后面加动词原形,即 had better do sth.不论主语是第几人称, 句子无论是何种时态,had better 形式不变。had better 的否定形式为had better not do sth 表示"最好不要做……"。如:You'd better not miss the last bus.
    You'd better not play on the road. It's dangerous.
    You'd better put on the coat. It's cold outside.
    4.Why not…?/Why don't you …?
    这两种句型结构常用于说话人向对方提出一个建议,意思是"不……?"; "为什么不……?"
    Why not…?/ Why don't you …? 后面必须跟动词原形。如:
    Why not go swimming?=Why don't you go swimming?
    Why don't you go out for a walk? =Why not go out for a walk?
    练习:
    一单项选择
    1. My mother was ill. I ______ stay at home to look after her.                        A. must          B. have to           C. could           D. can
    2. ---____ go shopping with your father?--- That's a good idea.                         A. Why don't     B. Why not      C. Do          D. Does
    3. You ___ give up smoking.              
    A. would better   B. had better     C. would better to  D. had better to
    4. Why don't you _____climbing with us tomorrow?                                        A. to go        B. going              C. go            D. goes
    5. Cars, buses and bikes ___ stop when the traffic lights changes to red.    
    A. can        B. may           C. must              D. need
    6. It's too hot. Perhaps you ______ swimming this afternoon.                      A. must  go         B. should go       C. may go       D. can go
    7. To make our hometown more beautiful, you __throw rubbish into the river.                                               A. needn't        B. mustn't         C. must        D. need
    8. How interesting the news is! Why _____ join us?                                   A. won't        B. no        C. don't                D. not

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