It was a serious problem with Apollo Thirteen.

VOA: special.2009.07.22

And it turned out that another, not quite as deadly, but still very serious disease called syphilis was also common in this part of the world at that time.

现在已知另外一种疾病,它并不完全致命但也很严重,它叫梅毒,在那时的一些地方也很常见

耶鲁公开课 - 生物医学工程探索课程节选

It was the most serious clash on the border since the Lebanon War four years ago, when Israel battled the Islamic guerrilla group Hezbollah.

VOA: standard.2010.08.03

He was distracted, he was going too fast, and it ended up causing one death and serious trauma and tragedy for the rest of the community."

VOA: standard.2010.06.24

It was the most serious border clash since the Lebanon War four years ago.

VOA: standard.2010.08.05