Дети катают мяч по полу.

The children are rolling a ball across the floor.

Breakdown of Дети катают мяч по полу.

• по: across
• ребёнок: the child
• пол: the floor
• мяч: the ball

Questions & Answers about Дети катают мяч по полу.

Why is дети used here, and what form is it?

Дети is the nominative plural form, because it is the subject of the sentence: the children are the ones doing the action.

A useful thing to know is that дети is an irregular plural. It corresponds to ребёнок (child) in the singular.

• ребёнок = child
• дети = children

So in this sentence, дети means children and is in the form you expect for the subject.

What is the infinitive of катают, and why is the verb in this form?

Катают comes from the infinitive катать.

Here it is in the present tense, 3rd person plural, because the subject is дети (they).

A quick breakdown:

• я катаю = I roll
• ты катаешь = you roll
• он/она катает = he/she rolls
• мы катаем = we roll
• вы катаете = you roll
• они катают = they roll

Since дети is plural, Russian uses the they form: катают.

Why is it катают, not катаются?