WordNet sense 1 (a request for information):

inquiring

WordNet sense 2 (marked by or given to doubt):

skeptical, doubting, sceptical

WordNet sense 3 (having or showing distrust):

distrustful

WordNet sense 4 (perplexed (as if being expected to know something that you do not know)):

quizzical

WordNet sense 5 (full or difficulty or confusion or bewilderment):

perplexed

WordNet sense 6 (showing curiosity):

inquisitive, speculative, wondering