9. 保留：keep = preserve = retain = hold
10. 有害于：destroy = impair = undermine = jeopardize
11. 减轻: ease = alleviate = relieve = lighten
★ 高频名词：
1. 影响：influence = impact
2. 危险：danger = perils =hazards
3. 污染：pollution = contamination
4. 人类：human beings= mankind = humane race
5. 老人： old people= the old = the elderly = the aged = senior citizens
6. 幸福：happiness = cheerfulness = well-being
7. 老师：teachers = instructors = educators = lecturers
8. 教育：education = schooling = family parenting = upbringing
9. 青少年：young people = youngsters = youths = adolescents
10. 优点：advantage = merits = superiority = virtue
11. 责任： responsibility = obligation = duty = liability
12. 能力： ability = capacity = power = skill
13. 职业： job = career = employment = profession