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Lesson 1 1
Lesson 2 4
Lesson 3 7
Lesson 4 10
Lesson 5 13
Lesson 6 16
Lesson 7 19
Lesson 8 22
Lesson 9 25
Lesson 10 28
Lesson 11 31
Lesson 12 34
Lesson 13 37
Lesson 14 40
Lesson 15 43
参考答案 46