I know why. I am learning Chinese and I want to say that, compared to English, Chinese have basically no grammar! English has set grammar rules, you have to memorise them, and then practice one grammar rule at a time. 你要多练习。照语法教书。如果你愿意，我可以帮你。当时你要知道：我的汉语不太好。

Grammar is difficult when you are learning a language. I think you have to practice it often in order to improve. Good luck!

What is rgrammar? Is this a computer program or something? Grammar in English can be tricky sometimes, but the basics are not too bad.