1. 与现在的事实相反:[If --- + were/did---, --- + would do---]
If I were you , I would marry him.
如果我是你,就会嫁给他。
2. 与过去的事实相反:[If --- + had done---, --- +would have done---]
If you had worked hard , you would have passed the exam.
如果你用功学习,就会通过考试了。
3. 与将来的事实可能相反:[If ---+ should do---, ---+ would do---]
If it should rain tomorrow , what would you do ?
如果明天下雨,你怎么办?
第二种:用在表示要求、建议、命令等的名词从句中中 华 考 试 网
从句谓语形式为:“---(should ) + do sth”(在美语中should常省去) 。
类似用法的动词有:
insist (坚持) , suggest (建议) , order(命令) , propose (建议) , demand (要求) , command (命令) , advise (建议) , desire (要求、请求) , request (请求) , require (需要、要求) , ask (要求) , prefer (宁愿), recommend(推荐) , arrange ( 安排) , advocate ( 拥护、提倡) ,maintain(坚决主张)等后面的宾语从句中。
第三种:用在“It + be + important (,necessary , natural , essential , strange , absurd , amazing , annoying , desirable, surprising , vital , advisable , anxious , compulsory , crucial , imperative , eager , fitting , possible , impossible , improper , obligatory , probable , preferable , strange , urgent 等, 以及insisted , suggested , ordered , requested , arranged , recommended 等) + that ---”结构中的that 引导的主语从句中
第四种:用在It is time that --- 结构中, 表示“该干某事了”, 含建议的意思, 用动词过去式。
It is time (that) we went to bed .
咱们该睡觉了。
注意: time 前可加about (表示“大约”) 或high(表示“强调”) 等。