Unit 1

Part Ⅰ Text Exercises

Part Ⅱ Exercises for PRETCO

Unit 2

Part Ⅰ Text Exercises

Part Ⅱ Exercises for PRETCO

Unit 3

Part Ⅰ Text Exercises

Part Ⅱ Exercises for PRETCO

Unit 4

Part Ⅰ Text Exercises

Part Ⅱ Exercises for PRETCO

Test yourself（for Units 1-4）

Unit 5

Part Ⅰ Text Exercises

Part Ⅱ Exercises for PRETCO

Unit 6

Part Ⅰ Text Exercises

Part Ⅱ Exercises for PRETCO

Unit 7

Part Ⅰ Text Exercises

Part Ⅱ Exercises for PRETCO

Unit 8

Part Ⅰ Text Exercises

Part Ⅱ Exercises for PRETCO

Test yourself（for Units 5-8）

Test yourself（for PRETCO—Level A）