1、第三课时(Grammar Focus3c)单元同步语法精讲精练含义：祈使句是用来表示请求、命令或建议等的一种句型。其主语一般为第二人称you，但通常省略。祈使句的句末一般用句号，表示较强语气时用感叹号。为了使祈使句显得更委婉、有礼貌，可在开头或结尾加上please。祈使句的四种类型Do型祈使句：实义动词原形其他eg：Listen to me，please.请听我说。Be型祈使句：Be动词其他eg：Be quiet，please.请安静。Let型祈使句：Letsb.动词原形其他eg：Lets play football.让我们踢足球吧。No型祈使句：No动词ing形式/名词！(表示禁止)eg：N
2、o smoking！禁止吸烟！No photos！禁止拍照！祈使句的否定形式通常是在谓语动词前加dont。但要注意以let开头的祈使句，其否定形式是：“Dontlet宾语动词原形其他”或“Let宾语not动词原形其他”。eg：Dont let him go swimming.Let him not go swimming.不要让他去游泳。情态动词can的用法can意为“能；会”，表示做某事的能力，其否定形式为cant。eg：Can you speak English？你会讲英语吗？can还可表示“允许；许可”。eg：You cant eat in class.你不能在课堂上吃东西。情态动词ha
3、ve to的用法have to意为“必须；不得不”，其后接动词原形。have to有第三人称单数形式，即has to。变疑问句和否定句要借助助动词do/does。eg：We have to go home after school.我们放学后必须回家。一、根据句意，用括号中所给单词的适当形式填空。1(clean)your room after you get up.2Please (bring)your dictionary to school next time.3(not)eat icecream after dinner.4No (swim)!5She has to (do)her ho
4、mework when she gets home.CleanbringDontswimmingdo二、按要求完成下列句子。每空一词。6You cant eat in class.(改为祈使句)in class.7We can play basketball after school.(改为否定句)We basketball after school.8Dont take photos here.(改为同义句)here.9Anna has to finish her homework today.(改为一般疑问句)Anna finish her homework today?10Bob has to go to bed before ten oclock(对画线部分提问)Bob to go to bed?Dont eatcant playNo photosDoeshave toWhendoes have
