Oh, Chinese TAs mostly understand no English, so they cannot control.

TAs are not meant to control, but to translate. The problem therein lies with the fact that the majority of them don't fully understand what you have said and therefore any translation is useless. TAs are not needed and only take up space in a class that is already overcrowded. If you as a teacher feel that you need a TA, then it only shows that your teaching methods are ineffective. English should be taught in English using as little Chinese as necessary. If you rely on TAs to do what you should be doing, then you are useless too.