Lesson one 1
Lesson Two 5
Lesson Three 11
Lesson Four 19
Lesson Five 27
Lesson Six 35
Lesson Seven 43
Lesson Eight 51
Lesson Nine 59
Lesson Ten 67
Lesson Eleven 75
Lesson Twelve 81
Lesson Thirteen 87
Lesson Fourteen 95
Lesson Fifteen 103
Lesson Sixteen 111
Lesson Seventeen 119
Lesson Eighteen 127
Lesson Nineteen 135
Lesson Twenty 143
Lesson Twenty-one 151
Lesson Twenty-two 159
Lesson Twenty-three 167
Lesson Thenty-four 175
参考答案 183