题干

下列反应氯元素只被氧化的是(   )

A:5Cl2+I2+6H2O=10HCl+2HIO3

B:MnO2+4HCl __ MnCl2+Cl2↑+H2O

C:2Cl2+2Ca(OH)2=CaCl2+Ca(ClO)2+2H2O

D:2HClO __ 2HCl+O2

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答案(点此获取答案解析)

B

同类题3

   About 21,000 young people in 17 American states do not attend classes in school buildings.
   Instead, they receive their elementary and high school education by working at home on computers. The center for Education Reform says the United States has 67 public “cyberschools(网络学校)” and that is about twice as many as two years ago.
   The money for students to go to a cyberschool comes from the governments of the states where they live. Some educators say cyberschools receive money that should support traditional public schools. They also say it is difficult to know if students are learning well.
Other educators praise this new form of education for letting students work at their own speed. These people say cyberschools help students who were unhappy or unsuccessful in traditional schools. They say learning at home by computer ends long bus rides for children who live far from school.
   Whatever the judgment of cyberschools, they are getting more and more popular. For example, a new cyberschools called Commonwealth Connections Academy will take in students this fall. It will serve children in the state of Pennsylvania from ages five through thirteen.
Children get free equipment for their online education. This includes a computer, a printer, books and technical services. Parents and students talk with teachers by telephone or by sending emails through their computers when necessary.
   Students at cyberschools usually do not know one another. But 56 such students finished studies at Western Pennsylvania Cyber Charter School recently met for the first time. They were guests of honor at their graduation.

同类题4

阅读理解

(Q = Question; A = Answer)

    Situation I

    Q: If someone sits right next to me in an empty movie theater, is it rude to move?

    A: Maybe, but nobody will fault you for it. Chances are that close sitter doesn't realize he disturbs you, so he may miss your annoyance. You undoubtedly aren't the first person he's met who needs enough room. Forgive his bad judgment, move quietly and enjoy the show.

    Situation II

    Q: If I use the bathroom at a store, do I need to buy something?

    A: Consider frequency and urgency. Is this a one-time or an emergency? If so, you don't have to buy anything, but it would be kind if you did. However, if you regularly use the bathroom at this place, then you are a customer, and you should act like one.

    Situation III

    Q: If someone is talking loudly on the bus, is there a nice way to ask him to keep it down?

    A: No. Try other means.1) Stare at him until he gets aware of it and quiets down. 2) Lift your finger in a silence motion(动作)and smile. 3) Put on earphones and ignore him.

    Situation IV

    Q: If I remember my friend's birthday a day late, should I apologize or just wish her a happy birthday like nothing happened?

    A: This is the reason why the word belated was invented. "Happy belated birthday!" is short for: "Well, I know I forgot, but then I remembered. Forgive me and happy birthday."

    Situation V

    Q: Can I lie about seeing a text because I was too busy or lazy to respond(回复) to it?

    A: Don't lie. Receiving a text does not mean you need to respond to it. Why waste a perfectly good lie when the truth will serve? "Yes," you can say if ever asked, "I saw it." No explanation is needed as to why you don't respond.