单项选择题
A．laughter and physical exercise have similar effects on the human body B．smile can produce the same effects as laughter C．pain can be reduced by laughter D．laughter is the best medicine
A．listened to sad music B．listened to pop music C．listened to different programs D．listened to a funny program
A．to give better condition to their patients B．to improve patients' health C．to make patients smile D．to prove smile and laughter lave the same effect