`Answer + Explai n :`

`1.` If you don't keep silent, you'll wake the baby up.

`2.` If you don't stop talking, you won't understand the lesson.

`3.` If I knew her number, I would ring her up.

`4.` If I had known the answer, I could have told you.

`5.` If we had had a map, we wouldn't have gotten lost.

`6.` If Susan hadn't eaten four cream cakes, she wouldn't have felt sick.

`7.` If he hadn't been late every day, he wouldn't have lost his job.

`8.` If Peter didn't eat so many chips, he wouldn't be fat.

`9.` If Robert hadn't started smoking cigarettes, he wouldn't have gotten a bad cough.

$------------$

`-` Cấu trúc If điều kiện loại `1 :` 

`->` If `+` S `+` V(s/es), S `+` will/can/shall `+` V(nguyên mẫu)

`-` Cấu trúc if câu điều kiện loại `2 :`

`->` If `+` S `+` V2/ed , S `+` would/could/should `+` V

`-` Cấu trúc if câu điều kiện loại `3 :`

`->` If `+` S `+` had `+` PII, S `+` would have `+` P`2`.