VOA慢速英语:Biden Decides Against Running for President

短语讲解：

1. And that prevents him from starting a presidential campaign, he said.

prevent from 阻止， 防止
例句：We must take steps to prevent this from happening again.
我们一定要采取措施，使这样的事不再发生。

2. At the age of 29, Joseph Biden was elected to the U.S. Senate.

at the age of 在…岁时
例句：He learned to ride a horse at the age of nine.
他九岁时学会了骑马。