shall和will做助动词都有表示将的意思,shall只在第一人称I\we后用,在现在的美式英语中很少用,听起来较正式,人们一般说will,如I will be late.英式英语中在提问题、建议或要求时用,如What shall I wear to the party?/Shall we order some coffee?/I'll drive,shall I?
shhould和would做助动词都有表示将的意思,在现代英语中, should 和 would 传统的区别已经没有了,口语中would的省略式'd 用得较多: I said I'd (I would) be late. / I'd (I would) really prefer tea.用在祈使句中表示委婉的语气:Would you mind opening the window?
should现在主要用于告诉别人他们应该做什么或给建议: You should really go and visit them soon. 也用在虚拟语气中.
过去式啊