Ответ:

1.Present Simple

1.Sam usually works very hard.

2.The gallery opens at 9 o clock.

3.These boys often play computer games.

2.Present Continuous

1.Tom is writing a letter now.

2.Julia is cleaning the room at the moment.

3.I am writing a test now.

3.Present Simple or Continuous

1.My mum always cooks well.

2.Paul is learning to drive a car now.

3.She prefers to rest abroad.

4.Past Simple

1.The lesson began 2 minutes ago.

2.Paul brought a car into the class.

3.Did you pay your bills yesterday?

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Если я правильно поняла,то любые три предложения из каждого упражнения.