Question

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Students use computers at their lessons
The teacher explained the rules of the game to the students 
Ann cooks a special dinner on the 21st of May
They arranged a nice picnic last month
The little boy drew these funny pictures

Answer 1

Computers are used by students at the lessons
The rules of the game were explained to the students by teacher
A special dinner on the 21st of May is cooked by Ann
A nice picnic was arranged last month by them
These funny pictures were drawn by the little boy.

by+.... можно убрать.