知乎

Zhihu, Chinese Q&A website modeled on Quora, at zhihu.com, launched in Jan 2011

to know / to be aware

(classical particle similar to 於|于[yu2]) in / at / from / because / than / (classical final particle similar to 嗎|吗[ma5], 吧[ba5], 呢[ne5], expressing question, doubt or astonishment)