其構(gòu)成形式如下：一、肯定式的類(lèi)型：1. be型（即：系動(dòng)詞原形be＋表語(yǔ)＋其它）.如： Be careful! Don't go too high. 當(dāng)心!別爬得太高. Be quiet, everyone! 大家請(qǐng)安靜!2. do型（即：行為動(dòng)詞＋賓語(yǔ)＋其它）.如： Come in, please!請(qǐng)進(jìn)來(lái)! Please open your books! 請(qǐng)翻開(kāi)書(shū)!3. let型（即：Let＋賓語(yǔ)＋動(dòng)詞原形＋其它）.如： Let me have a look.讓我看一看吧. Let me help you.我來(lái)幫你吧.二、否定式的類(lèi)型：祈使句的否定式多以do not（通?？s寫(xiě)為don't）引起,也可用never引起.1. be型（即：Don't＋be＋表語(yǔ)）.如： Don't be lazy! 不要懶惰! Never be late again. 千萬(wàn)不要再遲到了.2. do型（即：Don't＋行為動(dòng)詞原形＋其它）.如： Don't throw the ball like that.不要那樣扔球. Don't worry. I'll soon be all right.\x0d你們不要擔(dān)心,我很快就會(huì)好的. Never do it like that.千萬(wàn)不要那樣做了.3. let型有兩種否定形式： １）Let＋賓語(yǔ)＋not＋動(dòng)詞原形＋其它.如： Let him not go there.別讓他去那兒. Let's not waste time.咱們不要浪費(fèi)時(shí)間了. ２）Don't＋let＋賓語(yǔ)＋動(dòng)詞原形＋其它.如： Don't let her go there.別讓她去那兒.