1.与现在事实相反：谓语动词：would/could/might (not) do sth.

2.without有时可表示条件，引出虚拟语气，与but for大致同义

例句：Without your advice I would have failed.

假若没有你的劝告，我想必已失败了。

Without [But for] you, our project wouldn’t have succeeded.

如果没有你的话，我们的计划就无法成功了。