Welcome to EF, Penstaar! It takes most people quite along time to learn the basics of English grammar and there's no way you can master it in a matter of minutes. For your first example you should study conditional sentences; for the second, the plain/bare infinitive and for the third, clause types and the use of the infinitive.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
penstaarI guess the most difficult part if when I correct her and she says "Why?".. ummmI think you should say that you just don't know why, and put her in contact with an ESL tutor if that's possible.
Do I just say "Because that is the way it is"? Not sure what else to do.