题干

下列用高锰酸钾制取氧气的实验操作中正确的是(   )

A:检查装置气密性,先把手掌紧贴容器外壁,再把导管深入水中

B:加热时,先对试管预热,再对准药品部位加热

C:先往试管里装入药品,再检查装置气密性

D:收集气体结束时,先熄灭酒精灯,再把导气管移出水面

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B

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    Many children in England get given lunch at school. There are new rules about what children may be given for these lunches. The reason for this is to give children healthier food. There are many foods that children aren't allowed to eat and they're only allowed to eat small amounts of fatty or sweet food. If you were at a school there, you might hear this conversation as you wait for your lunch.

    Josh:        What's for lunch? I want chips!

    Dinner lady: No chips today. You've had chips twice this week already.

    Josh:        Oh! OK, I'll have a chicken pie with gravy.

    Dinner lady: No, sorry. You've had a pastry dish (油酥食品) once this week already.

    Josh:        Really?Oh, yes, on Monday. Well, what can I have? I'd like pasta and sauce.

    Dinner lady: No, sorry. Pasta counts as (算作)a pastry dish. So you can't have that, either.You've had two pastry dishes this week-a meat pie and a pizza. You can have vegetables or salad. The meatballs are nice today.

    Josh:        All right. I'll have meatballs and steamed vegetables. I hope they're tasty.

    Dinner lady: They're good for you!

    Josh:        I miss my chips. They're my favorite. I used to have them every day, before these new rules came in.

Dinner lady: Well, that's why these rules were brought in. Too many children were eating junk food, especially chips. Children like chips, but they aren't a healthy choice.

    Josh:        I'll have an apple juice with that, please.

    Dinner lady: OK, but its only 150 ml. You aren't allowed more than that as juice has sugar in it. The new rules encourage you to drink water. No soft drinks at all.

    Students cannot have more than two portions (价额)a week of food that has been deep-fired.They must have at least three different fruits and three different vegetables every week. Whole grains such as brown bread are to be given,instead of "white" grains.

    These rules are to teach healthy eating and to stop children putting on too much weight. This will make sure that more people are healthy in the future.