Ответ:
1. If you had set the alarm clock, you wouldn`t have been late for school.
2. If had known if was her birthday today, i would have sent her a card.
3. If i had heard the phone ringing, i would have answered it.
4. If you hadn`t wasted all your pocket money, you wouldn`t have had to borrow money from me.
5. This coat would have been cheaper, if I had bought it in the sale.
6. Sally wouldn`t have failed her exams if she had revised properly for them.
7. We would have played tennis if the grass hadn`t been wet.
8. He wouldn`t have crashed his car, if he hadn`t driven so fast.
Объяснение:
Это 3 условный тип предложений в англ. языке(III conditional) - В КОТОРОМ ГОВОРИТСЯ О ТОМ, ЧТО ЧТО-ТО ПРОИЗОШЛО В ПРОШЛОМ, НО ЭТОГО УЖЕ НИКАК НЕ ИЗМЕНИТЬ. ОБЫЧНО ИСПОЛЬЗУЕТСЯ ЧАСТО В ДИАЛОГАХ МЕЖДУ ЛЮДЬМИ.
ФОРМУЛА - If+had+v3/ved, (then) would+have/has+V3/Ved