单项选择题
A．Dangerous Sports; What and Why B．The Boredom of Modem Life C．Bungee Jumping: Is It Really Dangerous D．The Need for Excitement
A．they have a lot of free time B．they can go to hospital if they are injured C．their lives lack excitement D．they no longer need to hunt for food
A．are trying activities such as bungee jumping B．are climbing the highest mountains C．are close to death in sports D．are looking for adventures such as exploring unknown places