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．with words only B．in many different ways C．in letters and with drawings D．with smiles, tears and hands
A．Books. B．newspapers. C．TV and radios. D．A,B,C and others.