簡介
If it had rained last night, the ground would be wet now. 要是昨晚下過雨的話，現在地面就會是濕的。
You would be much better now if you had taken my advice. 假若你當時聽我的話，你現在就會好多了。
特別說明
條件從句用if I were…時，既可指現在也可指過去：
If I were you, I would stay. 我要是你我就會留下。
If I were you, I’d go to night school. 我要是你，我會上夜校。
If I were not busy, I would have come. 假若我不忙，我早就來了。
也可用if I had been you也表示過去：
If I had been you，I’d have taken the job. 我要是你，我就接受那份工作了。
通常情況下，在非真實條件句中主句和從句的謂語動詞所指時間是一致的，但有時也可能指不同的時間，這時要根據上下文的意思採用不同的謂語動詞形式
即：（有時if從句和主句所表示的假想情況時間不一致，如從句與現在事實相反，而主句表示與過去事實相反,那么句子兩部分的動詞形式應作相應的調整。）
e.g If I had asked her for advice yesterday, I should know what to do now.
You would be much better now if you had taken the doctor’s advice.
If my parents hadn’t forced me to come , I shouldn’t be here now.
If the weather had been more favorable, the crop would be growing still better.
假設語氣的兩個子句之間，時間有可能不同、必須分別判斷。例如：
If I had studied harder in school, I could qualify for the job now.
我在學校時要是有好好念書，現在就可以符合這項工作的要求了。
條件子句是過去時間（在學校時）的假設語氣，要退後成過去完成式(had
studied)來表示非事實。可是主要子句是現在時間(now)，只要用過去拼法的could
就可以表達非事實了，不需用到「過去+完成 (could have qualified)」。
