题目内容：
请在5处填写正确答案。
A．Recently，though，scientists changed their opinion after they studied a large group of nonsmokers． B．The Gilsons have been married for 35 years．
C．This smoke is called secondhand smoke．
D．However，secondhand smoke is dangerous to all people，old or young．
E．As a result．they have passed Iaws which p rohibit people from smoking in many public places．
F．In the United States．nine million children under the age of five live in homes with at Ieast one smoker
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答案解析：