"The girls listen."
Translation:Die Mädchen hören zu.
Zu is necessary because the verb zuhören means to listen. Hören alone would mean to hear.
Wait, why is "zu" separated from "hören" and inverted? Shouldn't it be "Die Mädchen zuhören"?
Many German verbs are separable-prefix verbs. The infinitive is zuhören, but whenever the verb is conjugated or in a main clause, the prefix is separated from the verb. This hasn't been introduced in Duolingo yet... But it will be soon. Separable-prefix verbs are definitely a headache for German learners!
I am wondering if "die Mädchen zuhören" would be acceptable, (since the separable verb might not need to be separated in such a short sentence)?
No, that doesn't work. In present tense the inflected verb is to be separated in a main clause.
Wenn die Jungen zuhören, dann hören die Mädchen auch zu.
is zu hoeren here in dative? can accusative be also used auf hoeren or hoeren auf? [ no umlauts on computer]. sorry. Sandra