doubtfully.

In a doubtful, uncertain, or ambiguous manner; hesitatingly, ambiguously, indistinctly.

in a doubted or doubtful manner; doubtfully: opposed to undoubtedly.

In a problematical manner; as a problem or question; doubtfully.

In a dubious manner; with doubt, doubtfully, hesitatingly; uncertainly, vaguely, ambiguously.

In a disputable manner or degree; questionably.

Without deciding or settling a question. rare.

In an indeterminable manner.

In a questionable manner.

in a dubitable manner.