虚拟语气中的would have done 与could have done结构 有什么 区别?什么时候用would什么

结构上并没有区别,选择would 或 could 要根据语境.
例如：
If he had waited one more minute,I would (could) have gone with him.
他只要再多等一分钟,我就会（能）和他一道走啦.两者皆可,但语意有点儿出入.
If he weren't so upset,I would have brought him along.
要不是他这么生气,我是会带他一块儿来的.would 比 could 要更强调是“我的”选择
Had I had enough money,I could have bought it without your help.
如果我钱够的话,我完全可以自己买的....这样的语气存有赌气的可能.