Unit 13 The USA 1
Unit 14 Roots 27
Unit 15 Study skills 49
Unit 16 Social and personal 71
Unit 17 My teacher 91
Unit 18 Office equipment 109
Unit 19 New Zealand 131
Unit 20 Gandhi 158
Unit 21 Who gets the money？ 180
Unit 22 Bees 198
Unit 23 The find of the century 221
Unit 24 Finding jobs 251
补充练习参考答案 281