题干

下列关于电解质溶液的判断正确的是

A:相同物质的量浓度的下列溶液中:①NH4Al(SO42、②NH4Cl、③CH3COONH4、④NH3·H2O,c(NH4)由大到小的顺序是:①>②>③>④

B:物质的量浓度相等的 H2S 和 NaHS 混合溶液中:
c(Na+) +c(H+) = c (S2―) +c(HS)+c(OH

C:HF比HCN易电离,则NaF溶液的 pH 一定比 NaCN 溶液小

D:常温下pH=6的酸性溶液中,不可能存在NH3·H2O分子

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    Emily and her boyfriend had just had a fight. She felt alone and hopeless. Then she went into the kitchen and grabbed what she needed before going back up to her room quietly. She switched on the TV and started eating…and eating…for hours, until it was all gone.

     What Emily didn't know at the time was that she was suffering from an illness called binge-eating disorder(BED)(暴饮暴食).

    For years, Emily didn't tell anyone what she was doing. She felt ashamed, alone, and out of control. Why don't famous people confess (承认) to BED, as they do to anorexia? It's simple: There's a stigma(污名)involved. “Overeating is seen as very bad, but dieting to be skinny is seen as positive and even associated with determination," says Charles Sophy, a doctor in Beverly Hills , California.

    "Some parents or friends may look at a teen with BED and think, 'Oh, a good diet and some will-power will do the trick.' But that's not true," says Dr.Ovidio Bermudez , a baby doctor at the Eating Recovery Center in Denver. "Eating disorders are real physical and mental health issues; it's not about willpower." The focus in treating BED shouldn't be on weight, because as with all eating disorders, the behaviors with food are a symptom of something deeper.

    Like most other diseases, genetics may play a big part in who gets BED and who doesn't. If you have a close relative with an eating disorder, that means you're more likely to develop an eating disorder of your own.

    Besides, many people with BED have tried at some point or another to control it by going on a diet, but paying more attention to food doesn't help. And it might even make things worse, like it did for Carla, who's 15 now and is recovering from BED. "My parents would always tease me about my weight, so when I was 14, I went on a very restrictive diet," she says. When you can't have something, you only want it more, so every time Carla would have a bite of something that wasn't allowed on her strict diet. She would quickly lose control and binge (狂欢).