Our inability to prevent weapons from being illegally smuggled across the border to arm these criminals causes the death of police officers, soldiers and civilians.

VOA: standard.2009.03.25

It's a mechanism that they have evolved in order to prevent foreign genes from entering a cell and being expressed.

它们进化出这种机制来,防止异源基因进入细胞并表达

耶鲁公开课 - 生物医学工程探索课程节选

It wasn't caused by the Fed's sudden tightening against inflation. It was different it was this recession was not understood not anticipated; the Fed came in late to cut interest rates to try to prevent it from being worse because it just didn't seem to have any reason for happening.

它不是由于美联储对通货膨胀的,突然紧缩政策造成的，它不同之处在于,这个经济衰退没有被理解，没有事先准备好；,美联储试图阻止它恶化而,降低利率为时已晚，因为,它似乎看起来没有任何理由发生。

耶鲁公开课 - 金融市场课程节选

More than 90 nations take part in the program, which involves intelligence sharing and naval coordination to prevent nuclear and other illegal weapons from being transported.

VOA: standard.2009.05.26

Opposition activists complain that internet speeds were brought to dismally slow levels and that they were forced to use proxies to prevent their IP addresses from being detected.

VOA: standard.2009.11.14

Yemeni Health Minister Abdul Karim Rasae, who chaired the conference, said the decision to prevent vulnerable people from attending this year's Hajj was debated long and hard before being approved.

VOA: standard.2009.07.23

"If you've ever worked on these cartel cases as I have as a prosecutor, you know a wall is not the best way to spend our dollars to prevent these drugs from coming into the United States and being able to apprehend and prosecute the smugglers themselves,".

VOA: standard.2009.03.24