英语播客EnglishPod 744

The Weekend - Adventure Sports
There is nothing quite like pushing the boundaries¹ of safe and bor-
ing. The rush from jumping out of an airplane or riding a huge
wave can really make you feel alive. In this lesson we talk about
adventure sports.

1 boundaries   

n.分界线( boundary的名词复数 )；范围；使球越过边界线的击球（得加分）；疆界

参考例句：

• Country boundaries are shown on this map as dotted lines. 这张地图上国界以虚线标出。
• The boundaries of that country were changed by a treaty. 那个国家的边界根据条约有所更动。 来自《简明英汉词典》