综合教程（3）学生自学辅导 1
Contents 1
Unit One Changes in the Way We Live 1
Unit Two Civil-Rights Heroes 42
Unit Three Security 78
Unit Four Extraterrestrials 107
Unit Five How to Celebrate Holidays 139
Unit Six The Human Touch 176
Unit Seven Making a Living 211
Unit Eight Cloning 255
Appendix Key to Supplementary Exercises 307