Present Simple - They do homework.
Present Continuous - They are doing homework.
Past Simple - They did homework.
Future Simple - They will do homework.
Present Perfect - They have done homework.
Present Simple - Alice skates in the park.
Present Continuous - Alice is skating in the park.
Past Simple - Alice skated in the park.
Future Simple - Alice will skate in the park.
Present Perfect - Alice has skated in the park.