Correct the mistake: "If you won’t buy a ticket before you go, you won’t get a seat at the concert. "
If you DON'T buy a ticket before you go, you won’t get a seat at the concert.
Correct the mistake: "If I was late to my lesson, the teacher gets angry."
If I AM/GET late to my lesson, the teacher gets angry.
Correct the mistake: "It’s dangerous to drive when it will snow hard."
It’s dangerous to drive when it SNOWS hard.