题干

中学化学中很多规律都有其使用范围,下列根据有关“规律”推出的结论合理的是

A:根据同周期元素的第一电离能变化趋势,推出Al的第一电离能比Mg大

B:根据主族元素最高正化合价与族序数的关系,推出卤族元素最高正价都是+7

C:根据溶液的pH与溶液酸碱性的关系,推出pH=6.8的溶液一定显酸性

D:根据较强酸可以制取较弱酸的规律,推出CO2通入NaClO溶液中能生成HClO

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D

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    The advice offered from any other 82-year-olds might have made young people yawn and roll their eyes. But when former South African president Nelson Mandela advised two dozen local youth leaders in Los Angeles to take education seriously, his audience was listening.

    The famed old man said to the young people that if they expected to improve the lives of others in the future, they must work at improving their own lives now. "Education is one of the most important weapons you have,” Mandela advised. “It will place you in a far better position to serve yourself and your community.”

     “The point is, he was young once and rebellious(叛逆的)once and he kept his dream alive, just as you each have dreams,” explained South Africa’s ambassador to the United States, Sheila Sisulu, as she introduced Mandela to the young crowd.

    Asked for specific advice about changing society by 21-year-old Ahmed Younis, Mandela suggested that somehow helping arouse more American interest in foreign affairs might be a start.

    There is an impression that Americans, in general, have not followed international developments properly, Mandela said. “I’m not making that statement myself, but there are serious political analysts who say Americans are not well informed as to what has happened in the world.”

    22-year-old Omari Trice said Mandela left him full of enthusiasm. “ He’s a person who set the tone for an entire nation, said Trice. “You come away feeling you need to be a superman in order to get things done.”