BBC在线收听下载:美国决定帮助乌克兰进行自卫

短语讲解：

1. Thousands of Yemenis have been protesting in several cities in the centre of the country against the political takeover by Houthi rebels.

in the centre of 在...的中间
例句：There is a flagstaff in the centre of the ground. 
操场中心有一根旗杆。 

2. Pressure has been mounting on the UAE to respond to claims made by American officials that safety concerns had led to it pulling out of coalition air strikes against the Islamic States two months ago.

lead to 导致
例句：He speculated that this might lead to a success. 
他推测这可能会导致成功。 
pull out of 退出，取消
例句：Our Australian partner pull out of the contract. 
我们澳大利亚合伙人退了合同。 

3. The alleged pullout was said to have taken place after Jordanian pilot Moaz al-Kasasbeh was captured in Syria in December after his jet crashed during a bombing mission.

take place 发生
例句：Earthquakes take place far underground. 
地震则发生在地球的极深处。 

4. Health officials say the rise is due to the country's prolonged drought in the heavily populated southern states.

due to 欠下债[账]，应给予; 由于
例句：The team's success was largely due to her efforts. 
该队的成功在很大程度上是由于她的努力. 

5. Security officials have said they won't be able to guarantee public safety if the poll goes ahead as planned because of the threat posed by Boko Haram Islamists.

be able to 能，会; 能够
例句：I admire the way she is able to shrug off unfair criticism. 
我很佩服她能对错误的批评意见不予理会。