In this paper, an analysis of Mandarin nandao-Qs is presented with a view to addressing the following questions: Are there dedicated words to express bias in natural languages? What is the nature of that bias? What are the syntactic and semantic properties of the dedicated bias words? With evidence from syntax, semantics, and discourse, I show that nandao is a dedicated bias word where the bias meaning is lexically encoded. The bias conveyed by nandao has a subjective epistemic modal meaning. On the other hand, nandao as a subjective epistemic modal adverb syntactically adjoins to ForceP to qualify the degree of speaker's belief towards the possible answers, and semantically expresses the bias meaning as not-at-issue content.