单项选择题
A．Adaptable. B．Flexible. C．Pliable. D．Yielding.
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