◇ The Third Conditional
第三類條件句
今天要說的文法是「和過去事實相反的」假設語氣，我們時常會想「要是當時那麼做，可能就 (不) 會這樣了吧。」這個「可能就 (不) 會」就是所謂的第三類條件式。我們想像和過去不一樣的情況，而會因此改變某個已經發生的結果。英文裡會用 If 引導從屬子句，來表達和過去事實不同的情況，而主要子句則表達希望發生的結果。句型為：「If + 過去完成式，would have + 過去分詞」。 舉例來說：The loud crunching and chewing of popcorn would have been a distraction from reading the subtitles. 雖然沒有 If 子句，不過從上下文可以推斷，若當時在戲院可以吃爆米花，大聲的咀嚼聲會造成觀眾分心。
Example：
1. If I had spotted the mistake, it wouldn't have caused her so much trouble.
如果我當時有發現失誤，我就不會造成她那麼多麻煩。
2. If I had known the consequences of my actions, I wouldn't have done it.
如果我知道我的行為造成的後果，我就不會這麼做。
3. Grace wouldn't have missed the deadline if she had managed her time well.
如果 Grace 時間安排得當，就不會錯過最後期限。