题干

有一包白色固体粉末,其中可能含有NaCl、Ba(NO32、CuSO4、Na2CO3中的一种或几种,现做以下实验:

①将部分粉末加入水中,振荡,有白色沉淀生成,过滤,溶液呈无色;

②向①的沉淀物中加入足量稀硝酸,固体完全溶解,并有气泡产生;

③取少量②的溶液,滴入稀硫酸,有白色沉淀产生;

④另取①中过滤后的溶液加入足量AgNO3溶液,产生白色沉淀.

根据上述实验事实,回答下列问题:

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    When asked about happiness, we usually think of something extraordinary, an absolute delight, which seems to get rarer as we get older.

    For kids, happiness has a magical quality: Their delight at winning a race or getting a new bike is unreserved (毫不掩饰的).

    In the teenage years, the concept of happiness changes. Suddenly it's conditional on such things as excitement, love and popularity. I can still recall the excitement of being invited to dance with the most attractive boy at the school party.

    In adulthood the things that bring deep joy-love, marriage, birth-also bring responsibility and the risk of loss. For adults, happiness is complicated (复杂的).

    My definition of happiness is “the capacity for enjoyment”. The more we can enjoy what we have, the happier we are. It's easy to overlook(忽视) the pleasure we get from the company of friends, the freedom to live where we please, and even good health.

    I experienced my little moments of pleasure yesterday. First I was overjoyed when I shut the last lunchbox and had the house to myself. Then I spent an uninterrupted morning writing, which I love. When the kids and my husband came home, I enjoyed their noise after the quiet of the day.

    Psychologists tell us that to be happy we need a mix of enjoyable leisure time and satisfying work. I don't think that my grandmother, who raised 14 children,had much of either. She did have a network of close friends and family, and maybe this is what satisfied her most.

    We, however, with so many choices and such pressure to succeed in every area, have turned happiness into one more thing we've got to have. We're so self-conscious about our “right” to it that it's making us miserable. So we chase it and equal it with wealth and success, without noticing that the people who have those things aren't necessarily happier.

    Happiness isn't about what happens to us-it's about how we see what happens to us. It's the skillful way of finding a positive for every negative. It's not wishing for what we don't have, but enjoying what we do possess.