目录 1
Unit 13 Albert Einstein 1
Lesson 49 1
Lesson 50 1
Lesson 51 2
Lesson 52 3
单元检测 4
Lesson 53 9
Unit 14 Satellites 9
Lesson 54 10
Lesson 55 11
Lesson 56 12
单元检测 12
Unit 15 A famous detective 18
Lesson 57 18
Lesson 58 18
Lesson 59 19
Lesson 60 20
单元检测 21
Unit 16 The sea 26
Lesson 61 26
Lesson 62 26
Lesson 63 27
Lesson 64 28
单元检测 29
Unit 17 Life in the future 33
Lesson 65 33
Lesson 66 34
Lesson 67 35
Lesson 68 35
单元检测 36
Unit 18 Mainly revision 42
Lesson 69 42
Lesson 70 42
Lesson 71 44
Lesson 72 45
单元检测 45