Unit 1 A Clean World or a Polluted World 1
Unit 2 The Web Lifestyle 13
Unit 3 The International Space Station 23
Unit 4 The age of Cloning 33
Unit 5 Genetic Discovery Brings Worries as Well as Hope 47
Unit 6 Classification of Small Dams 60
Unit 7 Chinese Gardens 72
Unit 8 The Internet Pushes News Out，You and Computers Are Pulling It Down 86
Unit 9 Civil Engineering 98
Unit 10 What Are Computers? 117
Unit 11 Green Buildings 130
Unit 12 The Method of Scientific Investigation 142
Unit 13 A Theory About Genius 153
Unit 14 The Costs of Safety 167
Unit 15 Patents and Inventions 180
Key to Exercises 192
Unit 1 192
Unit 2 195
Unit 3 197
Unit 4 199
Unit 5 202
Unit 6 205
Unit 7 208
Unit 8 211
Unit 9 214
Unit 10 217
Unit 11 219
Unit 12 222
Unit 13 224
Unit 14 227
Unit 15 229