虚拟语气:'不可能'假设

与现在相反

条件句：过去式（were）

主句：would+动词原形

If I were you I would not be such scheming.

与将来相反

条件句：should/were to+动词原形

主句：would/should/could/might+动词原形

If it should be clear day tomorrow,I would bath my dog.

与过去相反

条件句: had +动词过去分词

主句:would have +动词过去分词

If I had known you are such scheming,I would not have trusted you.

虚拟语气:愿望, 请求,建议，命令....

Wish

对现在的愿望: wish +动词过去式

I wish my neck don’t ached.

对过去的愿望wish + had/would have +动词过去分词

I wish I had protected my neck from indisposition.

对将来的愿望: wish + should/would/could/might/ +动词原形

I wish my neck could cured.

demand, suggest,insist, order...+should +动词原形