關於Conditional Sentences

I missed the school bus yesterday. If I had got up earlier, I would not have missed it.
had+pp I would+not+have+pp

Ann had a bad cold last Sunday. If she had not been ill, she would have joined us then.
had not+been would +have+pp


圖片參考：http://l.yimg.com/f/i/tw/ugc/rte/smiley_1.gif




2009-04-16 12:58:41 補充：
http://www.englisch-hilfen.de/en/grammar/if_type3.htm

這個網唔錯。

有教點Use

It is impossible to fulfil a condition which is given in the if-clause.
Form
if clause main clause
Past Perfect would + have + past participle
or
could + have + past participle
or
might + have + past participle

2009-04-16 12:58:49 補充：
Examples
If I had studied, I would have passed the exams.
If I had studied, I could have passed the exams.
If I had studied, I might have passed the exams.

2009-04-16 12:58:53 補充：
The if-clause can be at the beginning or at the end of the sentence.
If I had studied, I would have passed the exams.
I would have passed the exams if I had studied.