bezweifeln
to doubt
To have doubts about something; not to believe that something is true, correct, or possible.
Ich bezweifle stark, dass er sein Versprechen halten wird.
I strongly doubt that he will keep his promise.

to doubt
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to doubt
To have doubts about something; not to believe that something is true, correct, or possible.
Ich bezweifle stark, dass er sein Versprechen halten wird.
I strongly doubt that he will keep his promise.

'Bezweifeln' (to doubt) is an inseparable verb. The prefix 'be-' remains firmly attached to the verb stem 'zweifeln' in all conjugated forms and sentence types.
Er bezweifelte ihre Geschichte von Anfang an.
He doubted her story from the very beginning.
This verb requires a direct accusative object. This is an important difference from the verb 'zweifeln' (to doubt), which requires the preposition 'an' with the dative.
Die Expertin bezweifelt das Ergebnis der Studie.
The expert doubts the result of the study.
'Bezweifeln' (to doubt) is very often used with a subordinate clause introduced by 'dass' (that) or 'ob' (whether/if). The verb of the subordinate clause then comes at the end.
Ich bezweifle, dass er pünktlich kommen wird.
I doubt that he will arrive on time.
question
'in Frage stellen' and 'bezweifeln' mean very similar things: that you are not sure whether something is true, correct, or should apply. 'bezweifeln' says directly that someone has doubts. 'in Frage stellen' often sounds a bit more formal and can also mean that you critically examine the validity or value of something. In many situations, you can use both, especially when you do not simply accept a statement, decision, or explanation.

Die Fahrerin bezweifelt, dass der Bus wegen des Wetters pünktlich kommt.
The driver doubts that the bus will arrive on time because of the weather.
Die neuen Zahlen stellen den alten Plan in Frage.
The new figures call the old plan into question.