Unit 2 I'll help to clean up the city parks.
Unit 3 Could you please clean your room?
Unit 4 Why don't you talk to your parents?
Unit 5 What were you doing when the rainstorm came?
Unit 6 An old man tries to move the mountains.
Unit 7 What's the highest mountain in the world?
Unit 8 Have you read Treasure Island yet?
Unit 9 Have you ever been to a museum?
Unit 10 I've had this bike for three years.
附录：单元参考译文（Translation of the text）