uncertain; not settled
not trusting; questionable
"the candidate's doubtful past"
"he has a dubious record indeed"
"what one found uncertain the other found dubious or downright false"
"it was more than dubitable whether the friend was as influential as she thought"
"they were doubtful that the cord would hold"
"it was doubtful whether she would be admitted"
"dubious about agreeing to go"
"drew a few tentative conclusions"
A doubtful Passage in a Latin Poet.
The question whether certain doubtful forms should be ranked as species or varieties.
出自： C. Darwin
It was doubtful if he knew who Andrew Jackson was.
出自： Scott Fitzgerald
A change which is not an unquestionable improvement is a doubtful blessing.
出自： E. F. Schumacher