Will you water these flowers tomorrow? Cartoon film many times. - This sentence seems to be a combination of two unrelated phrases. It needs clarification or revision.

Betty always writes stories on the computer. - Correct.

Jocelyn had to make a report about animals for her science class. - Correct.

The librarian showed Cecily some good books. - Correct.

My brother has already made a chart for his report. - Correct.

Did the rabbit eat leaves and plants? - Correct.

You can see dinosaur bones in a natural history museum. - Correct.

Johnny didn't drink hot chocolate this morning. - Correct.

They should paint the gate slowly and carefully. - Correct.

Liz has to improve her listening skill in English. - Correct, but "skills" should be plural: Liz has to improve her listening skills in English.

Kenny is going to buy a new pair of shoes tomorrow. - Correct.

Shakespeare wrote "Hamlet". - Correct.

Someone built this house in 1990. - Correct.

My sister cleans the room every day. - "every day" should be two words.

A lion killed Mary's dog last week. - Correct.

Does Tom do these exercises carefully? - Correct.

They speak English and French in Canada. - "France" should be corrected to "French".

Her mother doesn't cook meals in the kitchen because of his laziness. - "His" should be corrected to "her" to maintain consistency with "Her mother".