Many children use the Internet to get useful knowledge and information, and to relax in their free time. But some of them are not using in a good way. Here are some rules to make sure you are safe and have fun on the Internet.
   Make rules for Internet use with your parents. For example, when you can go online, for how long and what activities you can go online.
Don't give your password (密码) to anyone else, and never leak out the following information---your real name, home address, age, school, phone number or other personal information. 
   Check with your parents before giving out a credit (信用) card number.
   Never send a photo of yourself to someone in e-mail unless your parents say it's OK. Check with your parents before going into a chat room. Different chat rooms have different rules and attract different kinds of people. You and your parents must make sure it's a right place for you.
   Never agree to meet someone you met on the Internet without your parent's permission (允许). Never meet anyone you met on line alone.
   Always remember that people online may not be who they say they are. Treat everyone online as strangers.
   If something you see or read online makes you uncomfortable, leave the site. Tell a parent or teacher right away.
   Treat other people as you'd like to be treated. Never use bad language.
   Remember—not everything you read on the Internet is true.

金属单质和非金属单质在一定条件下可以相互反应，生成相应的____ 或____ 。

如：Fe+S____

     2Fe+3C1₂ ____

     3Fe+2O₂ ____ 

器，是为了预防人类的敌人比我们先得到它……但到目前为止，我们既没有和平的保证，也

没有《大西洋宪章》所许诺的任何自由的保证。战争是赢得了，但和平却还没有”。由此可

见 (　　)

由Mg（OH）₂和MgO组成的混合物，测得其中含镁元素的质量分数为48%，取该混合物5g，将其投入115g的稀硫酸中恰好完全反应，所得溶液溶质的质量分数为（　　）