① 过去将来进行时：should be doing ， would be doing
例：The government promised that a new highway would be being built next July.
②有时可代替一般现在时，表达一种婉转、客气、礼貌、商量的语气。
如：
Would you mind my sitting here?您介意我坐在这里吗
③would have + 过去分词」用来表达过去想做的事，但却没做。
例：I would have called you， but I was too busy.我想打给你的，但我太忙了。(想打，但却没打)
④would(should)+动词原形 过去将来时常可用来表示过去习惯性的动作。此时，不管什么人称，一律用would。
例如：
1) Whenever she had time，she would do some reading. 她一有时间，总是看书。
2) I would play with them when I was a child. 当我还是孩童时，总是和他们一起玩。
