1. If / When … 過去簡單式 …, … 過去簡單式 …
2. … 過去簡單式 … if / when … 過去簡單式 …
- If my father went to a friend’s house for dinner, he usually took a bottle of wine or some flowers. But he doesn’t do that anymore. (如果我父親去朋友家共進晚餐，他通常會帶一瓶葡萄酒或一些花。但他現在不再這麼做了)
- When I had a day off from work, I often went swimming. Now, I never get time off. (當我休一天假時，我通常會去游泳。現在我都沒有休假)
- If the weather was nice, Mary often walked to work. Now, she usually drives. (如果天氣好的話，瑪麗經常走路去上班。現在她通常開車)
- Harry always helped me with my homework when he had time. But he doesn’t do that anymore. (當哈利有時間時，他都會從旁幫助我做家庭作業。但他現在不再這麼做了)
- A: Where did you stay if you went to Beijing? (如果你去北京，你都住哪裡？)
B: I usually stayed with my aunt. (我通常住我阿姨家)
Used to 是指過去習慣性和經常性的動作，但現在已經不做或不再發生，也可指過去存在的狀態或情況，但現在已不存在。這片語經常用於過去事實條件句來強調某事是過去的習慣。下面的例句與上面的例句意思並無不同。
- If my father went to a friend’s house for dinner, he used to take a bottle of wine or some flowers. But he doesn’t do that anymore.
- When I had a day off from work, I used to go swimming. Now, I never get time off.
- If the weather was nice, Mary used to walk to work. Now, she usually drives.
- Harry used to help me with my homework when he had time. But he doesn’t do that anymore.
- A: Where did you stay if you went to Beijing?
B: I used to stay with my aunt.
If / When
在過去事實條件句中，使用 if 或 when 都可以。若使用 if，則表示某事比較不常發生；若使用 when，則表示某事經常發生。
- When I had a day off from work, I usually went swimming.
- If I had a day off from work, I usually went swimming.
1. If … 過去完成式 …, … would have + 過去分詞 …
2. … would have + 過去分詞 … if … 過去完成式 …
- If I had owned a car, I would have driven to work. But I didn’t own one, so I took the bus. (如果我有車，我會開車上班。但我沒有車，所以我搭公車)
- Janet would have traveled around the world if she had had more money. But she didn’t have much money, so she never traveled. (如果珍妮有更多的錢，她會去環遊世界。但她沒有很多錢，所以她從未去旅行)
- Cindy would have gotten the job and moved to Paris if she had studied French in school instead of Japanese. (如果辛蒂在校時學的是法文而不是日文，那麼她會獲得那份工作並搬到巴黎)
- If Tony had worked harder, he would have earned more money. Unfortunately, he was lazy and he didn’t earn much. (如果東尼更努力工作，他會賺更多的錢。遺憾的是，他懶惰，所以沒有賺很多錢)
- A: What would you have done if you had won the lottery last week? (如果你上週中了樂透，你會做什麼？)
B: I would have bought a mansion. (我會買一間豪宅)
- A: What city would you have chosen if you had decided to move to China? (如果你已決定搬到中國，你會選擇哪個城市？)
B: I would have chosen Shanghai. (我會選擇上海)
過去非事實條件句只能使用 if，不可用 when，因為它談論的是與過去事實相反的虛構情況。
- I would have bought that car if it had been cheaper. (如果那部車便宜一點，我會買下它) (正)
- I would have bought that car when it had been cheaper. (誤)
在過去非事實條件句中，除了 would 外，還可使用 should, could, might 這三個情態助動詞。
- If Robert had invited me, I really should have gone. (如果羅伯特邀請我，我真的應該去)
- If you had gone to Egypt, you could have learned Arabic. (如果你去埃及，你就能學阿拉伯語)
- If Cindy had had time, she might have gone to the party. (如果辛蒂有時間，她可能參加派對)