VOA慢速英语:In Fight Against Troubling Viruses, Vaccines Offer Hope

1. threaten vt. 危及; 恐吓; 预示（某事）; 预示凶兆
例句：He said army officers had threatened to destroy the town
他说陆军军官们曾威胁要摧毁那座小镇。

2. infect vt.使受影响，感染; 传染
例句：A single mosquito can infect a large number of people.
一只蚊子就可以感染很多人。

3. appear vi.发表; 出现，显现
例句：They appear to be very sensitive to mildly corrosive environments.
它们似乎对轻度的腐蚀环境非常敏感。

4. emerge vi.出现，浮现; 暴露
例句：Richard was waiting outside the door as she emerged
她出现的时候，理查德正在门外等着。

5. avoid vt.避开，避免，预防
例句：The pilots had to take emergency action to avoid a disaster
飞行员不得不采取紧急措施避免灾难的发生。

6. vaccinate vt.给…接种疫苗
例句：Dogs must be vaccinated against distemper
狗必须接种犬瘟热疫苗。

7. decrease vi. 减少，减小
例句: Gears on an automobile may be used either to decrease or increase speed.
汽车的排挡可用来加速或减速。

8. lengthen vt.延长; 伸长
例句：The evening shadows were lengthening
残阳下的影子越拉越长。