Breakdown of De tas is spoorloos, dus ik moet hem in de trein zijn vergeten.
ik
I
zijn
to be
in
in
de trein
the train
Questions & Answers about De tas is spoorloos, dus ik moet hem in de trein zijn vergeten.
Why does this sentence use zijn vergeten instead of hebben vergeten for 'have forgotten'?
The verb vergeten (to forget) is unusual because it primarily uses zijn as its perfect auxiliary rather than hebben, especially when it means leaving an object behind. Therefore, 'to have forgotten' translates to the perfect infinitive zijn vergeten, which pairs with the modal moet to express a past deduction.
How exactly does the grammar of moet ... zijn vergeten map to the English 'must have forgotten'?
English expresses this deduction with a modal plus a perfect infinitive: 'must' + 'have forgotten'. Dutch uses the exact same logic: the present tense modal moet (must) combined with the perfect infinitive zijn vergeten (to have forgotten). Because it is a normal main clause after dus, moet takes the second position and pushes the infinitives to the end.
At the end of the sentence, could I say vergeten zijn instead of zijn vergeten?
Yes! In a Dutch verb cluster at the end of a clause, the auxiliary verb (zijn) and the past participle (vergeten) can go in either order. Both zijn vergeten and vergeten zijn are perfectly correct and natural here.
Why do we use the pronoun hem (him) to refer to a bag (de tas)?