If you receive an e-mail that looks something like this:

    ARE YOU GOING TO CLASS TODAY? How does reading this message make you feel? Why did the sender use all capital letters(大写字母)? Was he or she angry, or did that person just forget to turn off the 'Cap Lock' on the computer? The fact is, this e-mail is usually the way that people shout online. Knowing when and when not to use capital letters is just one example of online etiquette(礼仪) —often called 'netiquette'. Virginia Shea's book, Netiquette, lists a basic set of dos and don'ts for communicating suitably with others on the Internet. Following are some of her suggestions.

    First, always remember that you are sending messages to a real person, not just to a computer. Don't type anything that you wouldn't say to someone's face. Also, remember that the person who receives your message cannot hear the tone of your voice, or see the expression on your face, so make sure your meaning is clear.

    Don't do anything online that you wouldn't do in real life. Don't take anything without paying for it, unless it's free. Don't use information that someone else has written, and say it's yours. Don't read other people's e-mail—you wouldn't open your next-door neighbor's mailbox and open their mail, right? Do share your knowledge of the Internet with others. It's a big place with lots of information, and there are many new things to discover.

    Remember that people judge(判断) you by your words as well as your actions, so try to write well. Good writing skills, as well as correct grammar and spelling, matter(有关系). Send polite, well-written e-mail messages to others. If you're uncertain about how to spell a word or which phrases to use, look it up. There are lots of helpful books and websites.

    It's okay to show your ideas online in forums(论坛) like chat room or message boards, but don't start arguments with people. 'Flame wars' in online discussions can be interesting to read, but are often unfair to other members of the group. Express your opinions, but remember that fighting online or offline is just not suitable.

    When you're online, just as in 'real' life, try to respect(尊重) other people's space, privacy and feelings. Remember, you are not the only one travelling on this highway!

一物体做初速度为零的匀加速直线运动到达位移为x、2x、3x处的速度之比是（     ）

1850-1870年的法国，煤产量从不到450万吨增至1,333万吨；钢产量从28万吨增至101万吨……。20年内工业总产值增长两倍，对外贸易额增长三倍。农业也开始由工业装备起来，化肥、脱粒机、收割机、刈草机的使用日益普遍。由材料可以得出的深层历史结论是

两个锐角的和一定大于直角．

资料分析:

中国营养学会将我国成年人钙供给量定为0.8克／天，处于生长发育旺盛阶段的青少年对钙的需求量更高，但我国绝大多数人远未达到这个标准。据调查显示，我国95％的儿童存在不同程度的缺钙，北京、上海、内蒙古地区小学生钙的摄入量分别只有标准量的33%、55%、69%。可见，我国儿童缺钙的现象比较普遍，也比较严重。

请仔细阅读上面的资料并回答以下的问题。