BBC在线收听下载:中国在南海捕获美国无人潜艇

短语讲解：

1. No evacuation convoys have left Aleppo for the past eight hours, raising concerns for thousands of people still thought to be trapped in the remaining rebel enclave.

thousands of 数千的
例句：The library attracts thousands of scholars and researchers.
那个图书馆吸引了成千上万的学者和研究人员。

2. The evacuation was suspended after pro-Syrian government militias demanded that a reciprocal deal must be carried out for two villages besieged by rebels.

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。