15．Healthy eating 1
16．Fire! 18
17．Nature 41
18．The necklace 61
19．Jobs 85
20．Mainly revision 111
Revision Exercise(Unit 15—20) 126
21．Karl Marx 142
22．Britain and Ireland 170
23．Rescuing the temple 191
24．The science of farming 214
25．At thd conference 234
26．Mainly revisiom 257
Revsion Exercise(Unit 21—26) 280