A user is being abusive to me. He is adding comments that have no relation with my question, and is attacking me in Chinese. Maybe moderators do not understand Chinese, so nobody is deleting them.
In this question for example:
https://math.stackexchange.com/questions/3113958/element-in-finite-number-of-borel-subgroups
Can I block that user? But I do not know how to block the user.
I do not know how to deal with this problem. I need help.