Unit 1 Pesos in the Sea 1
Unit 2 Early Days of the Mail 8
Unit 3 The Vanished City 16
Unit 4 Man Hunters of the U.S.A 24
Unit 5 Emergency Jump 32
Unit 6 The Gift of Fire 40
Unit 8 What Makes the Weather 56
Unit 9 Icarus 64
Unit 10 The Cowboy's Bandanna 72
Unit 11 Why Study Math? 79
Unit 12 California's Gianst 88
Unit 13 The Big Wind 96
Unit 14 A Pound of Butter 104
Unit 15 Beauty on the Witng 112
Unit 16 Death of a Gull 120
Unit 17 Postmen with Feathers 128
Unit 18 The Beau Cather 136
Unit 19 How Stanley Found Livingstone 144
Unit 7 Disaster in Dayton 148
Unit 20.Traveling in the Jungle 152
Unit 21.He Led a Useful Life 160
Unit 22 Rain Is Born. 168
Unit 23 Elas Kills a Buffalo 176
Unit 24 A Roof over Our Heads 184
Unit 25 Rubber 192
Unit 26 The History of Books 200
Unit 27 Horace Greeley 208
Unit 28 Looking Nice 216
Unit 29 Animal Education 225
Unit 30.Arctic Adventure 230
Answer Key(另附) 241