BBC在线收听下载:世卫组织称寨卡疫区回国人士应禁欲6个月

短语讲解：

1. Rescue workers in the rebel-held side of the Syrian city of Aleppo say government helicopters carried out a chlorine gas attack using barrel bombs.

carry out 进行; 执行; 完成
例句：The Social Democrats could still carry out their threat to leave the government
社会民主党人仍有可能将其退出政府的威胁付诸实施。

2. Dozens of people were reportedly left struggling to breathe.

dozens of 很多
例句：Dozens of doctors and nurses have been working day and night for weeks
很多医生和护士已经夜以继日地工作数周了。