本句的意思是,如果我们有时间的话,我们就已经完成工作了（事实上我们没有时间,与事实相反,要用虚拟语气）
表示与过去事实相反的虚拟条件句.其句子结构为：
从句：If + 主语+ had +过去完成式动词+ ……
主句：主语+ would (should,could,might) + have +过去完成式动词+……
例如:
⑴、If you had taken my advice,you would not have made such a mistake.如果你听了我的劝告,就不会犯这样的错误.（事实上你没有听我的劝告）
在非真实条件状语从句中,谓语动词按正常情况“后退一步”.也就是：
①与过去事实相反,在从句中用过去完成时形式表示.
②与现在事实相反,在从句中用过去一般时形式表示.
③与将来事实可能相反,在从句中用过去将来时形式表示.
主句中则用情态动词would,should,could 等加一个与从句一致的动词形式.例：
⑴、If I had come her yesterday,I would have seen him.
⑵、If I were a teacher,I would be strict with my students.
⑶、If it should snow tomorrow,they couldn't go out.