回複：我當時是這樣做的。

What you did "如果他按照我的要求把分數改成A，沒有人會有任何損失，但如果他不改，我就義無反顧的搞到DEAN甚至校長那裏去。" is illegal in any country including China. Such act is called "threaten someone to achieve the benefit".

Your professor was so nice to you. He gave you A not because of your threatening, but he was helpless on you, a Chinese!