1.過去的情況： If we had found him earlier, we could have saved his life.要是我們當時早點找到他的話，我們就可以救活他。 →Had we found him earlier, we could have saved his life.
2.現在或將來的情況： If she were here, she would attend the meeting too. 如果她在這裡，她也參加會議。 →Were she here, she would attend the meeting too.
3.將來的情況： If it should rain tomorrow, we should have to stay at home.若明天下雨，我們只好呆在家裡。 →Should it rain tomorrow, we should have to stay at home. 注意：若遇到否定詞not時，不能與were/should/had縮略為Weren’t/Shouldn’t/Hadn’t而置於句首。 如：If I hadn’t warned you, you could have been killed. 正確：Had I not warned you, you could have been killed. 錯誤：Hadn’t I warned you, you could have been killed.
1.過去的情況： If we had found him earlier, we could have saved his life.要是我們當時早點找到他的話，我們就可以救活他。 →Had we found him earlier, we could have saved his life.
2.現在或將來的情況： If she were here, she would attend the meeting too. 如果她在這裡，她也參加會議。 →Were she here, she would attend the meeting too.
3.將來的情況： If it should rain tomorrow, we should have to stay at home.若明天下雨，我們只好呆在家裡。 →Should it rain tomorrow, we should have to stay at home. 注意：若遇到否定詞not時，不能與were/should/had縮略為Weren’t/Shouldn’t/Hadn’t而置於句首。 如：If I hadn’t warned you, you could have been killed. 正確：Had I not warned you, you could have been killed. 錯誤：Hadn’t I warned you, you could have been killed.