一般現(xiàn)在時怎樣變否定句

一般現(xiàn)在時怎樣變否定句一般現(xiàn)在時怎樣變否定句一般現(xiàn)在時變否定句的規(guī)則. (a) 含有 am is are 的句子,變否定句時, 只需在am is are 后加not. 例1 This is a book. 否定句 This is not a book . 例2 I am a teacher . 否定句I am not a teacher . 例3 These are pens . 否定句These are not pens . (b) 含有實義動詞的句子，變否定句分兩步。 （1）如果主語是第三人稱單數(shù)時，要在實義動詞前加doesnt,后面的動詞用原形。 例1 He eats an apple. 否定句 He doesnt eat an apple. 例2 Jim does his homework. 否定句 Jim doesnt do his homework. 例3 Marry goes to school. 否定句Marry doesnt go to school. (2) 如果主語不是第三人稱單數(shù)時，只 需在實義動詞前加dont. 例1 I teach English. 否定句 I dont teach English. 例2 They go to school. 否定句 They dont go to school. 例3 We sing a song. 否定句 We dont sing a song. (c) 含有情態(tài)動詞的句子,變否定句時, 只需在情態(tài)動詞后加not. 例1 I can dance. 否定句 I can not dance. 或 I cant dance. 例2 They can speak English. 否定句 They can not speak English. 或 They cant speak English. 例3 He must go home. 否定句 He must not go home. 或 He mustnt go home. 例4 He must be on the playground. He can not be on the playground. 析：當must be用來表示推測，有“一定”的含義時， 否定式要用can not. 例5 You must say something at the mecting. You neednt say anything at the mecting. 析：當“must+行為動詞”用來表示“必須”的含義時， 其否定式可用neednt 或mustnt表示“不需要”，“不必”， 語氣委婉，must not表示“禁止”，“千萬別”語氣生硬。 例6 You may come in now. You mustnt come in now. 析：may作為情態(tài)動詞表示“可以”時， 其否定式用must not,而不用may not. 例7 He may watch TV . He mustnt watch TV. 注意: (1) 見到some 變否定句時,要換成any. 例1 I eat some apples. 否定句 I dont eat any apples. 例2 He has some books. 否定句 He doesnt have any books. 例3 He does his home work. 否定句 He doesnt do his home work. (2) 見到and 變否定句時,要換成or. 例1 There is some air and water on the moon. 否定句 There isnt any air or water on the moon. 例2 He has some brothers and sisters. 否定句 He hasnt any brothers or sisters. 例3 He eats apples and oranges. 否定句He doesnt eat apples or oranges. (3) 見到too和also變否定句時,要換成either. 例1Tom goes to school too. 否定句 Tom doesnt go to school either. too和also用于肯定句中時，否定句中用either替換。 （4 見到alr