Personal obligation (должен, должна)

To say that someone "must" or "has to" do something, Russian uses the word должен. As a short-form adjective, it agrees with the gender and number of the person who has the obligation. Notice the fleeting vowel -е- in the masculine form, which drops out in the other forms.

MasculineFeminineNeuterPlural
должендолжнадолжнодолжны

To state what someone must do, follow the correct form of должен with an action verb in the infinitive.

Daily Duties and Chores

This structure is heavily used for talking about household chores and daily responsibilities.

Asking Questions and Contrasting Duties

To ask about responsibilities, place a question word like кто (who) or почему (why) at the beginning of the sentence. You can also contrast different people's chores in a single sentence using the conjunction а (and/but).

I must wash the floor, and my sister must wash the dishes.
Я должен мыть пол, а сестра должна мыть посуду.