Thank you, Lawrence. I also quit studying English for a lot of time. Fortunately, I like reading, so I am learning from some books. I think it's better to lean like everyday life, in various ways; reading, listening to a radio, watching some movie, using YouTube, etc. And I can say there are lots of errors in our mother tongue. This is natural. Learning a foreign language is difficult like a life.

Thank you for your comment. ^_^! 

I've been studying English about three years.

At the first year, I always wanted to give up. Sometimes I wanted to kill myself. If I gave up, then I got nothing. If I  kept going, there was no hope totally. What I decided to do is to push myself on a higher position at the beginning. I bought several  novels by English native writers. You can image, for one page, I needed to read more than ten times to understand the content. I spent about two hours everyday to read. It sill costed me months to finish a book. 

From the second year, I decided to learn business English. It was the first time that I found it seemed that I knew nothing about English. Even I could read some books, and I could understand some videos. In real conversations. Native speakers could not understand me, I could not understand them in most time. I noticed that I had so many bad habits in learning English. From pronunciation to grammar, to expressions, to misunderstanding of phrase verbs. How sad I was at that moment! So I gave up learning business English. I decided to relearn English like a beginner. Got started with basic pronunciation. 

Something changed about half of year ago. I bought some courses in my filed offered by western Universities. It means that in those course, lecturers won't care about your language abilities. I found that I can understand almost all of content in those courses.