Unit10 When Was It Built？ 1
Unit11 Planting Trees 7
Unit12 Mainly Revision 14
Unit13 The World s Population 22
Unit14 Shopping 30
Unit15 A Doctor For Animals 38
Unit16 The Football Match 46
Unit17 The Missing Necklace 55
Unit18 Mainly Revision 63
期末测试题 71
参考答案 79