重点讲解：
1. at risk of 处境危险；有风险的；在危险中；
Everybody who goes into this region, whoever they are, is at risk of being taken hostage.
进入这个地区的人，不管是谁，都有被劫为人质的危险oH-#IR]er!7hE!,4。
2. gain the upper hand 上风；优势；有利地位；
The two sides were so well-matched that neither could gain the upper hand.
旗鼓相当，胜负难分-NZ+9RO&h)2WzN2。
3. return to 重新开始，继续（某项活动）；
At that stage he will be 52, young enough to return to politics if he wishes to do so.
那时他将会是52岁，还很年轻，如果他希望的话，仍可重返政坛H%FfWTGE~Y.IW34RQ#LY。
4. due to 由于；因为；
Mistakes due to carelessness may have serious consequences.
由粗心大意造成的错误有可能带来严重的后果fLS5MvEgwBXh|_。