In 2000, the World Health Organization (WHO) announced that China was already a polio-free country.

2000年，世界卫生组织（WHO）宣布中国已成为一个没有脊髓灰质炎的国家。

youdao

The region is polio-free, and has been for ten years.

该区域已经有十年无脊髓灰质炎。

youdao

Its main task is to monitor the polio-free status of the region.

其主要任务是监测该区域的无脊髓灰质炎状况。

youdao

In 2011, India, considered the most difficult place to achieve eradication, was declared polio-free.

WSJ: Bill Gates and Michael Bloomberg: Our Plan to Eradicate Polio

The shootings, in a series of attacks, represent a major setback in the quest for a polio-free world.

BBC: Polio killings a major setback

Infected travellers had carried the virus to nearly 20 previously polio-free countries causing more than 1200 polio cases.

BBC: Polio killings a major setback