There is nothing unethical about asking someone to review their article before they turn it in to a teacher. Virtually every teacher out there strongly encourages people to have others review their work before turning it in. Tony Chen, please feel free to post more of your articles. There is no difference between asking people here to review them and asking a friend or family member to review your homework. What you did is both smart, polite, and ethical.

you should be a little more patient.

I did it. But, its unethical. While everybody is writing of their own, you are using a refined version. Of course you will not tell your teacher the secret behind a flawless article in English, thus giving him a false impression. In other words, you will be appreciated for what you didnt do.