Dear Piyanuch PLOY Rojvanit:
Hi Piyanuch, Grammar, in any language, is just a set of rules for the user to follow in order to speak the language understandably. We can learn to speak without knowing the mechanics of grammar just like we've learned how to speak our native language. But it is difficult for you now because you've been conditioned to study English grammar since you first started studying English. Don't worry too much about grammar. Remember that language is communication and even if you use the wrong grammar, people will understand you. Also remember that making grammar mistakes is probably the best way to improve your grammar if you learn from them. As your English fluency improves so will your grammar usage. All you have to do is try to improve your fluency by practicing a lot and if you do this, your grammar will automatically improve. Therefore, don't worry and join as many complementary classes, social clubs, workshops and English corner's as possible to practice, OK? Take care --- Dr. English