实验室用过氧化氢溶液制取氧气，要得到平稳氧气流的操作正确的是（　　）

—All right. I____ him later.

    American people like to say “Thank you” when others help them or say something kind of them. People of many countries do so, too. It is a very good habit.

    You should say “Thank you” when someone passes you the salt on the table, when someone walking ahead of you keeps the door open for you, when someone says you have done your work well, or you have bought a nice thing, or your city is very beautiful. “Thank you” is used not only between friends, but also between parents and children, brothers and sisters.

    “Excuse me” is anther short sentence they use. When you hear someone stay behind you, you know that someone wants to walk to past you without touching you. It's not polite to break others when they are talking. If you want to speak to one of them, say “Excuse me” first, and then begin to talking. You should also do so when you begin to cough or make any noise before others.

一位摄影记者写到：“在一个偏远的地方，我看到一群成年人，一副无所事事的懒散样子，眼神都是呆滞的，原来他们没有上过一天学。我觉得自己没有办法帮他们了，我只能拿着相机摄下那些八九岁仍然背着草筐、拉着山羊的孩子，以引起社会的关注。因为如果没有人帮他们，这些孩子又过三五年，又是一群文盲。他们不是不想上学，而是没有条件上学。这些孩子，只要有个机会，给他们一点阳光，他们就灿烂；你只要让他们上学，给点儿雨露，他们就滋润……”

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