本期内容：

The World Health Organisation declared Liberia free of Ebola, ending an outbreak in west Africa which has killed more than 11,000 people. The WHO says the disease could still flare up again. Scientists announced encouraging news on a new treatment. No vaccine yet exists, though Vladimir Putin said Russia had developed one; he gave no further details.

词义解析:

Outbreak: 爆发
Flare up：爆发
Encouraging：鼓舞人心的
Treatment：治疗方法
Vaccine：疫苗