Поставьте глагол в правильное время в пассивном залоге 1. The rule explained by the teacher at the lasy lesson ( to understand)

1. The rule explained by the teacher at the last lesson was understood by all of us. — Правило, объясненное учителем на последнем уроке, было понято всеми нами.

Passive voice is formed with the help of the auxiliary verb to be + verb+ed or if the verb is irregular the third form of the verb.

Was the rule explained by the teacher at the last lesson understood by all of us?

The rule explained by the teacher at the last lesson was understood by all of us, was not it?

What was understood by all of us?

Was the rule explained by the teacher or by my friend at the last lesson understood by all of us?