一般現(xiàn)在時(shí)變否定句的規(guī)則.

一)、主語+be動詞

含有 am is are 的句子,變否定句時(shí),只需在am is are 后加not.

【例】This is a book. 否定句 This is not a book .

I am a teacher . 否定句I am not a teacher .

These are pens . 否定句These are not pens .

二)、主語+實(shí)義動詞

含有實(shí)義動詞的句子，變否定句分兩種。

1、如果主語是第三人稱單數(shù)時(shí)，要在實(shí)義動詞前加doesn't,后面的動詞用原形。

【例】He eats an apple. 否定句 He doesn't eat an apple.

Jim does his homework. 否定句 Jim doesn't do his homework.

Marry goes to school. 否定句Marry doesn't go to school.

2、 如果主語不是第三人稱單數(shù)時(shí)，只需在實(shí)義動詞前加don't.

【例】I teach English. 否定句 I don't teach English.

三)、主語+情態(tài)動詞

含有情態(tài)動詞的句子,變否定句時(shí), 只需在情態(tài)動詞后加not.

【例】 I can dance. 否定句 I can not dance. 或 I can't dance.

They can speak English. 否定句 They can not speak English. 或They can't speak English.

【注意】He must be on the playground. He can not be on the playground. 析：當(dāng)must be用來表示推測，有“一定”的含義時(shí)， 否定式要用can not.

You must say something at the mecting.否定句 You needn’t say anything at the mecting.

析：當(dāng)“must+行為動詞”用來表示“必須”的含義時(shí)，其否定式可用needn’t 或mustn't表示“不需要”，“不必”， 語氣委婉，must not表示“禁止”，“千萬別”語氣生硬。

You may come in now. You mustn't come in now.

析：may作為情態(tài)動詞表示“可以”時(shí)， 其否定式用must not,而不用may not.

四)、注意

1、含有have和has的句子變成否定句

have和has，變否定句不能在have和has后加not，則需要助動詞來幫助解決。

have→do not have或don’t have

has→does

not have或doesn’t have (has要變成have)

【例】I have a pen. 否定句I don’t have a pen。

My father has a watch. 否定句 My father doesn't have a watch.

2、見到some 變否定句時(shí),要換成any.

【例】I eat some apples. 否定句 I don't eat any apples.

He has some books. 否定句 He doesn't have any books.

He does his home work. 否定句 He doesn't do his home work.

3、見到and 變否定句時(shí),要換成or.

【例】There is some air and water on the moon.

否定句 There isn't any air or water on the moon.

He has some brothers and sisters.

否定句 He hasn't any brothers or sisters.

He eats apples and oranges.

否定句He doesn’t eat apples or oranges.

4、見到too和also變否定句時(shí),要換成either.

too和also用于肯定句中時(shí)，否定句中用either替換。

【例】Tom goes to school too.

否定句 Tom doesn’t go to school either.

5、a lot of (=lots of)變?yōu)閙any或much。

【例】They have a lot of friends.(可數(shù)名詞)

否定句They don't have many friends.

There is lots of orange in the bottle.(不可數(shù)名詞)

否定句There isn't much orange in the bottle.

6、見到already變否定句時(shí),要換成yet。

【例】He has had supper already.

否定句 He hasn’t had supper yet.

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