20.2 比较and和or

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1) 并列结构中,or通常用于否定句,and用于肯定句。 2) 但有时and 也可用于否定句。请注意其不同特点: There is no air or water in the moon. There is no air and no water on the moon. 在否定中并列结构用or 连接,但含有两个否定词的句子实际被看作是......

18.4 限制性和非限制性定语从句

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1) 定语从句有限制性和非限制性两种。限制性定语从句是先行词不可缺少的部分,去掉它主句意思往往不明确;非限制性定语从句是先行词的附加说明,去掉了也不会影响主句的意思,它与主句之间通常用逗号分开,例如: This is the house which we bought last mo......

16.5 特殊的虚拟语气词:should

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1) It is demanded / necessary / a pity + that…结构中的主语从句的谓语动词要用should 加动词原形, should 可省略。 句型: (1)suggested It is (2)important that…+ (should) do (3) a pity (1)suggested, ordered, proposed, required, demanded, re......

4.8 as + 形容词或副词原级 + as

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1)在否定句或疑问句中可用so… as。 He cannot run so/as fast as you. 2)当as… as 中间有名词时采用以下格式。 as +形容词+ a +单数名词 as + many/much +名词 This is as good an example as the other is. I can carry as much paper as you can.. 3)......

3.19 many, much

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Many,much都意为"许多", many + 可数名词,much + 不可数名词。 How many people are there at the meeting? How much time has we left? Many of the workers were at the meeting. Much of the time was spent on learning.......

21. 情态动词

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21.1 情态动词的语法特征 1) 情态动词不能表示正在发生或已经发生的事情,只表示期待或估计某事的发生。 2) 情态动词 除ought 和have 外,后面只能接不带to 的不定式。 3) 情态动词没有人称,数的变化,即情态动词第三人称单数不加-s。 4) 情态动词没有......

21.1 情态动词的语法特征

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1) 情态动词不能表示正在发生或已经发生的事情,只表示期待或估计某事的发生。 2) 情态动词 除ought 和have 外,后面只能接不带to 的不定式。 3) 情态动词没有人称,数的变化,即情态动词第三人称单数不加-s。 4) 情态动词没有非谓语形式,即没有不定式......

21.2 比较can 和be able to

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1)can could 表示能力;可能 (过去时用could), 只用于现在式和过去式(could)。be able to可以用于各种时态。 They will be able to tell you the news soon. 他很快就能告诉你消息了。 2)只用be able to a. 位于助动词后。 b. 情态动词后。 c. 表示过去某......

21.3 比较may和might

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1) 表示允许或请求;表示没有把握的推测;may 放在句首,表示祝愿。 May God bless you! He might be at home. 注意: might 表示推测时,不表示时态。只是可能性比may ......

21.4 比较have to和must

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1) 两词都是'必须'的意思,have to 表示客观的需要, must 表示说话人主观上的看法,既主观上的必要。 My brother was very ill, so I had to call the doctor in the middle of the night. 我弟弟病得很厉害,我只得半夜里把医生请来。(客观上需要做这件事)......

21.5 must表示推测

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1) must用在肯定句中表示较有把握的推测,意为"一定"。 2) must表对现在的状态或现在正发生的事情的推测时, must 后面通常接系动词be 的原形或行为动词的进行式。 You have worked hard all day.You must be tired. 你辛苦干一整天,一定累了。(对现在情况......

21.6 表示推测的用法

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can, could, may, might, must 皆可表示推测,其用法如下: 1)情态动词+动词原形。 表示对现在或将来的情况的推测,此时动词通常为系动词。 I don't know where she is, she may be in Wuhan. 2)情态动词+动词现在进行时。 表示对现在或将来正在进行的情况......

21.7 情态动词+ have +过去分词

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1) may(might) have + done sth, can (could) have + done sth 表示过去,推测过去时间里可能发生的事情。 Philip may (might) have been hurt seriously in the car accident. Philip can (could) have been hurt seriously in the car accident. 2) must h......

21.8 should 和ought to

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should 和ought to 都为"应该"的意思,可用于各种人称。 ---Ought he to go? ---Yes. I think he ought to. 表示要求,命令时,语气由 should(应该)、had better最好)、must(必须)渐强。......

21.9 had better表示"最好"

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had better 相当于一个助动词,它只有一种形式,它后面要跟动词原形。 had better do sth had better not do sth It is pretty cold. You'd better put on my coat. She'd better not play with the dog. had better have done sth表示与事实相反的结果,意......

21.10 would rather表示"宁愿"

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would rather do would rather not do would rather… than… 宁愿……而不愿。 还有would sooner, had rather, had sooner都表示"宁愿"、"宁可"的意思。 If I have a choice, I had sooner not continue my studies at this school. I would rather stay he......

21.11 will和would

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注意: 1)would like; Would like to do = want to 想要,为固定搭配。 Would you like to go with me? 2)Will you…? Would you like…? 表示肯定含义的请求劝说时,疑问句中一般用some, 而不是any。 Would you like some cake? 3)否定结构中用will,一......

21.12 情态动词的回答方式

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问句 肯定回答 否定回答 Need you…? Yes, I must. No,I needn't Must you…? /don't have to. 典型例题 1)---Could I borrow your dictionary? ---Yes, of course, you____. A. might B. will C. can D. should 答案C.could表示委婉的语气,并不为时态。答......

21.13 带to 的情态动词

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带to 的情态动词有四个:ought to, have to, used to, be to, 如加上have got to ,(=must), be able to,为六个。它们的疑问,否定形式应予以注意: Do they have to pay their bill before the end of the month? She didn't use to play tennis before she......

21.14 比较need和dare

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这两词既可做实义动词用,又可做情态动词用。作为情态动词,两者都只能用于疑问句,否定句和条件句。 need 作实义动词时后面的不定式必须带to,而dare作实义动词用时, 后面的to 时常可以被省略。 1) 实义动词: need (需要, 要求) need + n. / to do sth 2......