My favorite sport skiing教案

s2: no, he ought not to be rude to his opponent.
(這部分是按照書上的情景對話，讓學生在情景中自然的使用了情態動詞，這種練習比較生活化，對學生來說也比較簡單，但是還不足以掌握情態動詞的更加深入的用法，所以在下一個步驟，教師有必要將主要的情態動詞做系統講解。但是要把握難易度，不易太難。)
step three: basic use of model verbs

1）表示義務。意為“必須”（主觀意志）。
1.we must do everything step by step.  
2.you mustn’t talk to her like that.
3. --must we hand in our exercise-books now?
--no, you needn’t. / no, you don’t have to.  
mustn’t是“不許”、“決不能”的意思，不是“不必”。因此在例3中否定回答用needn’t
2）表示揣測。意為“想必、準是、一定”等，只用于肯定句。否定句往往用can’t，因為mustn’t是“不許”，“決不能”的意思。
1. he must be ill. he looks so pale.  
否定：he can’t be ill. he is so energetic.
2. carol must get very bored in her job. she does the same thing every day. 。
否定： carol can’t be very bored in her job. she does different things every day.
對過去發生的事情表示揣測。
i’ve lost one of my gloves. i must have dropped it somewhere.
practice:
1. come on! we __________ hurry because there isn’t much time left.
  a. may    b. must    c. can    d. need
2.  amy did best in the english test. she __________ hard last week.
  a. must have worked   b. should have worked    
  c. should work        d. must work
keys: 1. b   2. a

must表示主觀意志，而have 重在客觀因素。但有時候must和have to 可以互換。
1. she’s a really nice person. you must meet her.
2. i haven’t phoned ann for ages. i must phone her tonight.
practice:
translation:
1. 他的視力很差，不戴眼鏡無法讀書。
his eyesight isn’t very good. i have to wear glasses for reading.
2. 好長時間沒有給ann聯系了，我今晚必須給她打個電話。
you can’t turn right here. you have to turn left.
總結：must基本用于現在時，除在間接引語中可用于表示過去時間外，其它情況用“have to”。

1. should 
1) should表義務。意為“應該”（某件事宜于做），用于各種人稱。語氣沒有must強烈。
you should be polite to your teachers.  
you shouldn’t waste any time.  
2）表推測，意為“想必一定、照說應該、估計”等。
the film should be very good as it is starring first—class actors. 
they should be home by now.  
3) 表看法或建議
the government should do more to help homeless people.
do you think i should apply for the job?
4）表期待
 she’s been studying hard for the exam, so she should pass.