Contents序言 ⅢUnit Ⅰ：A Taste of America 1
Chapter 1 A Family Sees America Together 2
Chapter 2 The All-American Diner 13
Unit Ⅱ：Family Life 25
Chapter 3 How Alike Are Identical Twins? 26
Chapter 4 The Search for Happiness through Adoption 37
Unit Ⅲ：Technology on Earth and in Space 51
Chapter 5 Laptops for the Classroom 52
Chapter 6 The International Space Station：A World Project 63
Unit Ⅳ：Healthy Living 75
Chapter 7 The Dangers of Secondhand Smoke 76
Chapter 8 A Healthy Diet for Everyone 90
Unit Ⅴ：International Scientists 107
Chapter 9 Alfred Nobel：A Man of Peace 108
Chapter 10 Marie Curie：A Twentieth-Century Woman 120
Unit Ⅵ：The Earth's Resources and Dangers 133
Chapter 11 Oil as an Important World Resource 134
Chapter 12 How Earthquakes Happen 149
Index of Key Words 165
Answer Key 173