Unit1-1 After the Great Fire
Unit1-2 Language Learning
Unit1-3 The Enormous Strength
Unit1-4 The Standard of Living
Unit2-1 bicycles
Unit2-2 Children and Education
Unit2-3 Two Types of People
Unit2-4 Economic Systems
Unit3-1 England's Railway lines
Unit3-2 A Ship of Ice
Unit3-3 Kurzweil Reading Machine
Unit3-4 Shipment
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附录