Questions & Answers about Дети верили в магию.
Дети means children. It is the irregular plural of ребёнок (child).
So:
- ребёнок = child
- дети = children
Russian has a number of irregular plural forms, and this is one of the most common ones.
In this sentence, дети is in the nominative plural, because it is the subject of the sentence.
Верили is the past tense plural form of верить (to believe).
It matches the subject дети, which is plural.
Compare:
- он верил = he believed
- она верила = she believed
- они верили = they believed
Since дети = children, the verb must also be plural: верили.
In Russian, past tense verbs agree with the subject in gender and number, not person.
The past tense endings are:
- -л for masculine singular
- -ла for feminine singular
- -ло for neuter singular
- -ли for plural
So верили is plural because дети is plural.