I agree the sooner you can move away from English the better, but keep in mind your Chinese level is above most users on the site (nice job!). I'd vote for bilingual. Reason being, some of the questions do have explanations, but I can't understand the explanation as I feel it is another question. I have to spend 20 minutes looking up words in the explanation to understand it! If I can't understand the explanation it is no more useful than knowing the right answer to the question.

Either way though, I'll take any explanation over none :).