Unit 1 How tall are you?
Unit 2 Last weekend
Unit 3 Where did you go
Unit 4 Then and now
Recycle Mike's happy days
Appendix 1：Songs in each unit
Appendix 2：Words in each unit
Appendix 3：Vocabulary
Appendix 4：Useful expressions
Appendix 5：Proverbs
Appendix 6：Short plays
Appendix 7：Irregular verbs
Appendix 8：English pronunciation patterns
