Today, I studied a important point English grammar.

Capitalize the pronoun I

How funny!
This oversight is undoubtedly my fault. Given that I have read extensively in English, I should have noticed this error long ago.

Anyway, I now know what my problem is. Even when I was using Chinese, I noticed there are many rules about the language; but Chinese is grammatically flexible, so even if I don’t follow the rules it hardly causes any problems and I didn’t pay much attention to them. English, however, is different.

Perhaps I should to look up and study these rules more carefully.
By the way, I have now capitalized the previously lowercase “i.”