If he isn't careful, he would break them.
incorrect (he will break them)
If I buy one of those, I won't be hungry anymore.
correct
If he don't get up now, he'll be late for school.
incorrect (if he doesn't...)
If he doesn't practice, he won't never play in a band.
incorrect (he'll never play)
If you don't take an umbrella, you'll getting wet.
incorrect (you'll get wet)
If you won't get wet, you won't catch a cold.
incorrect (if you don't get wet)
If I am have a good computer, I will be able to study well.
incorrect (If I have a good computer,)
If I can't borrow your dress, I won't go to the party.
correct
If I don't go to the party, I won't meeting anyone.
incorrect (I won't meet)
If I talking to you now, I will miss the bus.
incorrect (If I talk to you )
If he miss the bus, he'll be late for work.
incorrect (If he misses the bus)
If you lose something, you'll find it in the last place you look.
correct
If you arrive early at a party, everyone else will late.
incorrect (everyone else will be late)
If you make an appointment with the doctor, you'll feel better before you see him.
correct
If you not do your homework, your teacher will asking you for it.
incorrect (If you don't do your homework, your teacher will ask you for it.)
If you buy a new carpet, you drop something on it the first day.
correct
