Greetings, Lena, and welcome to the Forums! You are right about the general rule of using tenses in the conditional clause introduced by if and other similar subordinators. However, there is a number of exceptions which you should be able to recognise.
New words, one handy idiom, and a 2-minute quiz — delivered to your inbox to keep your streak alive.
Lena876I guess you are RussianNot really, my friend, though I've always had a deep sense of respect for Russian people. Thanks for a good note. Good luck in the Forums!