英語語法：肯定句變否定句
在做練習時，有些題目會要求我們將肯定句變爲否定句，這類題型要求同學們能夠熟練掌握兩種句型之間的轉換。並不是所有的否定句都能由肯定句加上否定詞構成，在進行轉換時也有一些細節問題值得注意，下面跟隨小編一起來看一下吧。
首先我們要將陳述句按其所包含的謂語部分分成三類：謂語是be動詞的肯定句、謂語是實義動詞的肯定句與謂語是情態動詞的肯定句。
謂語是be動詞的肯定句轉換爲否定句
直接在be動詞後加not。如：is not，are not，am not，was not，were not。
He is a math teacher. → He is not a math teacher.
They were players of the school team. → They were not players of the school team.
謂語是實義動詞的肯定句轉換爲否定句
在動詞前加助動詞否定形式don’t/doesn’t/didn’t，動詞的第三人稱單數形式或過去式都轉變爲動詞原形。
He wants to go out. → He doesn’t want to go out.
We had a picnic in the park yesterday. → We didn’t have a picnic in the park yesterday.
謂語是情態動詞的肯定句轉換爲否定句
直接在情態動詞後加not。
He can remember the content in detail. → He can not remember the content in detail.
There will be a new building next year. → There will not be a new building next year. (will not可以縮寫爲won’t)
大多數情況下，肯定句轉換爲否定句只要直接加一個not就可以，但這種情況並不絕對。還有一些需要注意的點，肯定句中的some在否定句中要換成any，在be動詞和多數情態動詞之後的not可以縮寫成n’t，不過也有例外，如won’t。
