大伙都说could, might, would, should 为 can, may, will,shall 的过去式,但在有时候并不表过去,而是“愈加委婉”,如you can't / couldn'tcriticize him. 你不该批评他。can/could i help you? 有哪些能助你的。请问我想表达“过去你不该批评他”,“过去有哪些能助你”还是用could吗?
过去你不该批评他:You shouldn'thave criticized him.
过去有哪些能助你吗?(这个汉语句子本来就不够通顺)。Was there anything that I could have helped to do?