1、用在“wish+宾语从句”中，表示很难实现或不能实现的愿望，可以翻译为“但愿…”, “悔不该…”等。表示现在不能实现的愿望，从句的谓语动词用过去式；表示将来的愿望，从句的谓语动词用“would(could)+动词原形”；对过去的事情表示愿望，从句的谓语动词用“had+过去分词” 或“could + have + 过去分词”。Wish 后面的宾语从句必须用虚拟语气，不管这个愿望是否能实现。如：
I wish it were spring all the year round.
I wish you could go with us.
We wish we had arrived there two hours earlier.
2、用在as if/as though, 或even if/eventhough引导的从句中: 这时，如果从句中表示的动作发生在过去，则谓语动词用had＋过去分词形式；如果指的时现在的状况，则用过去式 (be用were)；指将来则用would(should,could)+动词原形。这里只看从句动作发生的时间，与主句的时态没有关系。
Some metals look at first sight as though they weregold.
He looked as if he were an artist.
He speaks English so fluently as if he had studiedEnglish in the U.S.
He always sounds as if he would help you.
3、在It is (high)time (that)…句型中，后面的从句的谓语动词常用过去式 (be的过去式用were), 或用should+ 动词原形 (should 不能省略) 来表示。这句话的意思是“（现在）该…”。
It is time we left/should leave.
It is high time that you got married.
It is time that I bought a car.
4、在 I would rather(that)…句型中，后面的从句的谓语动词用过去式 (be的过去式用were)。这句话的意思是“我宁可…”，表示说话人的意愿。
I’d rather I were in the rain now.
I’d rather you did not tell him.
5、在表示建议、要求、命令等意思的动词，如arrange,command, demand, desire, insist, order, propose, request, require, suggest,beg, move（提议）后面的宾语从句中，谓语动词用should+ 动词原形，should可以省略，而引导宾语从句的that 不能省略。例如：
We suggested that we (should) have a meeting.
We insisted that they (should) go with us.
The doctor ordered that she (should) stay in bed fora few days.
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