亚磷酸（H₃PO₃）是二元酸，H₃PO₃溶液存在电离平衡：H₃PO₃⇌H⁺+H₂PO₃^﹣．亚磷酸与足量NaOH溶液反应，生和Na₂HPO₃．

（1）①写出亚磷酸与少量NaOH溶液反应的离子方程式　____ ．

②根据亚磷酸（H₃PO₃）的性质可推测Na₂HPO₃稀溶液的pH____ 7（填“＞”、“＜”或“=”）．

③某温度下，0.1000mol•L^﹣1的H₃PO₃溶液中c （H⁺）=2.5×10^﹣2 mol•L^﹣1，除OH^﹣之外其他离子的浓度由大到小的顺序是　____ ，该温度下H₃PO₃电离平衡的平衡常数K=____ ．（H₃PO₃第二步电离忽略不计，结果保留两位有效数字）

（2）亚磷酸具有强还原性，可使碘水褪色，该反应的化学方程式____ ．

（3）电解Na₂HPO₃溶液也可得到亚磷酸，装置示意图如下：说明：阳膜只允许阳离子通过，阴膜只允许阴离子通过．

①阴极的电极反应式为____ 　．

②产品室中生成亚磷酸的离子方程式为　____ ．

    When Alice was sixteen, I was the one who wanted to run away from home. It was 1 to see the changes coming over her. She skipped school, and refused to communicate. I tried being firm, but it didn‘t 2. I saw a dark future for my once sweet daughter.

    One school day Alice returned home very late. With a quarrel in view. I was surprised to see Alice was 3.

     “I hope I did the right thing, Mom,”“Alice said. I saw a cat, all bloody but alive. I 4it to the vet's(宠物医院), and was asked to make payment 5. As I couldn't reach anyone at the phone number on the cat's tag(标牌), I had to pay the bill.”

    In the following days, the owner still couldn't be 6. Alice paid the vet to continue treatment. I grew 7: what if the family had simply left the cat behind?

    A week went by. A woman called to speak to Alice.

    “She is at school,” I said.

    “You have a 8daughter,” she said, apparently in tears.

    Her family had just returned from abroad, and got a (n) 9 from the vet. Their cat was recovering, thanks to Alice's 10. “We can't wait to hug Cuddles again,” she sobbed.

    Upon her return home, Alice was filled with 11at the news. So was I. I learned through another woman's eyes that my daughter was still a good person despite her 12teenage years. Her warm heart would surely guide her in the right direction.

    “This is your last chance,” warned Mrs Gillfeather. I broke out in a sweat and my hands started to shake. We both wanted to get to sleep, but before we could, I had to put a cannula(针管) in her arm.

    Before becoming a doctor I'd only a vague idea what a cannula was, coming from an hour spent with a plastic arm while at medical school. Once I became a doctor, however, I couldn't seem to get away from them.

    For those of you who are lucky enough to have never come into contact with one, they're tiny little tubes that are put into a vein(静脉)so that fluid or medicines can do directly into the blood. That's the theory. Unfortunately, the problem is that for them to work, you have to get them into the vein in the first place. This tends to be trickier than you'd imagine—and it's a job that tends to fall on the junior doctors.

    Mrs Gillfeather's veins were particularly elusive that evening. I'd been jabbing the needle in for at least 20 minutes.

    “Isn't there someone else who could do this?” she asked, for the fourth time. “Someone who knows what they're doing, perhaps,” she said under her breath, just loud enough for me to hear.

    Finally, I got it in. Mrs. Gillfeather and I both breathed a sigh of relief

    Just as I was about to leave the ward, the nurse called me over, “Max, there's another cannula to do on bed 16.”

下列说法中正确的有（  ）
①同位角相等.  ②凡直角都相等. ③一个角的余角一定比它的补角小.
④在直线、射线和线段中，直线最长. ⑤两点之间的线段的长度就是这两点间的距离.
⑥如果一个角的两边分别平行于另一个角的两边，则这两个角一定相等.