Help me with my homework again pls and ty

Luis nervously answered the questions about how he had collected water samples in an empty plastic jugs and what he had concluded. He showed them the control groups , plain tap water and bottled water, and samples he took from a river, a pond and a drinking fountain. Luis explained how he used a water testing kit to test the waters purity and pointed at the results he had graphed.

The judges wanted to know how hiroko collected samples in different parts of the town. Hiroko told them that hiroko had put large circles of sticky paper on index cards and then tacked each card up where hiroko thought that there was a pollution from cars and factories. Hiroko also had to explain the chart hiroko made of hiroko's result.

active voice: my father cut the tree.

passive voice: the tree was cut by my father.

active voice: people buy newspapers every day.

passive voice: newspapers are bought (by people) every day.

active voice: people have been using movies as political propaganda since world war ii.

passive voice: movies have been used as political propaganda since world war ii.

active voice: donna gave me my birthday present.

passive voice: i was given my birthday present (by donna). / my birthday present was given to me (by donna).

active voice: mom will leave the keys on the counter.

passive voice: the keys will be left (by mom) on the counter.

the words in parentheses are the agent of the passive voice and can be omitted when obvious, generic, or simply unnecessary.