标题：非洲现已无脊髓灰质炎，这是一个重大里程碑
来源：每日英语听力，VOA常速_健康
It's taken decades and millions of health workers, traveling by foot, boat and any other way they had to immunize children from polio.
immunize v.（尤指通过注射疫苗）使免疫
immunize sb/sth (against sth)（尤指通过注射疫苗）使免疫
polio n. 小儿麻痹症；脊髓灰质炎
Health workers have even braved conflict to prevent a horribly crippling disease. We've made tremendous progress, working with community leaders, sometimes with military officials, to help deliver vaccine to reduce the number of children that were inaccessible due to conflict down to very very small numbers.
brave adj.勇敢的；无畏的；需要勇气的；表现勇敢的
v.勇敢面对；冒（风险）；经受（困难）
brave sb/sth 勇敢面对；冒（风险）；经受（困难）
crippling v. “cripple”的现在分词
adj. 造成严重后果的；有严重后果的 causing severe damage or problems
tremendous adj. 1.巨大的；极大的 2.极好的；精彩的；了不起的
vaccine n. 疫苗
n.1.a preparation containing weakened or dead microbes of the kind that cause a disease, administered to stimulate the immune system to produce antibodies against that disease
2.a software program that protects a system against a computer virus
3.a substance put into the body, usually by injection, in order to provide protection against a disease
reduce down to 减少到
Twenty years ago African governments committed to eradicate polio. Since then nine billion oral polio vaccines have prevented nearly two million cases of wild polio virus on the continent. The global polio eradication initiative provided funding and logistical support.
eradicate v. 根除；消灭；杜绝 -> eradication n.
logistical a. 后勤的，物流的
The effort also involved a huge disease surveillance network to check sewage for the virus and test cases of paralysis.
surveillance n. 监督；监控；监测
sewage n. （下水道的）污水，污物
1.human and domestic waste matter from buildings, especially houses, that is carried away through sewers
2.waste substances, especially waste from people’s bodies, removed from houses and other buildings by a system of large underground pipes called sewers
paralysis n. 麻痹；瘫痪 (这里可以看作polio的同义替换)
That's because polio still exists along the border between Pakistan and Afghanistan, until the virus is knocked out of this region.
knock out of 从……中敲出来；把…敲出；从…敲出来(意思比较生硬，就是病毒在这片区域销声匿迹之时)
I hope that some of those assets that have been deployed in the polar eradication effort, will then be used to hold on to the gains that we have made, not only on polio but on routine immunization, to ensure that every child everywhere in the world, is able to be protected from vaccine preventable diseases. The polio eradication effort demonstrates two things, that people around the world can come together to accomplish great things.
hold on 继续；不挂断
1.to wait, especially for a short while
2.to continue on a course of action or direction or maintain something such as a set of principles or a particular state of mind
最后一句没什么生词，就是觉得这句句子可以在作文中借鉴。