Subject: Mobile phone problem

Dear Editor,

    I am a middle school student. I used to bring a mobile phone with me during school hours. But the teachers think using mobile phone is distraction (分散注意力的事) to students during school hours and also causes so much trouble in class. So now we aren't allowed to bring mobile phones to school.

    I find it really inconvenient (不方便的)。 My parents feel unhappy because they can't get in touch with me(不能与我有联系) . But I can't make our school change this rule. What do you think I should do to solve this problem?

Liu Fengyi

    This morning Jenny, Linda, Mary, Alice and Sally found five bags. Jenny found a brown bag in Classroom 208. In the bag is ____. Linda found a purple bag in Classroom 306.In the bag is ____. Mary found a green bag in Classroom 409.In the bag is ____.Alice found a red bag ____.In the bag is a yellow pencil. Sally found a blue bag ____.In the age is a watch.

学习的目的是在于应用．请根据你所掌握的化学知识，解释或解决以下生活中的一些常见问题．

（1）金刚石和石墨物理性质不同的原因是 ____；

（2）要区分一氧化碳和二氧化碳两种无色气体，可采用的方法是 ____；（写一种即可）

（3）为保证人身安全，进入久未开启的菜窖前，须做 ____试验；

（4）北宋画家张择端用墨绘制的《清明上河图》能够保存至今，是因为 ____