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。
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。
Before a WHO region can be certified polio-free, three conditions must be satisfied.
世卫组织区域要获得无脊髓灰质炎认证，必须满足三个条件。
Before a WHO region can be certified polio-free, three conditions must be satisfied.
世卫组织区域要获得无脊髓灰质炎认证，必须满足三个条件。
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