阔里吉思，性勇毅，习武事，尤笃于儒术，筑万卷堂于私第，日与诸儒讨论经史，性理、阴阳、术数，靡不该贯。尚忽答的迷失公主，继尚爱牙失里公主。宗王也不干叛，率精骑千余，昼夜兼行，旬日追及之。时方暑，将战，北风大起，左右请待之，阔里吉思曰：“当署得风，天赞我也。”策马赴战，骑士随之，大杀其众，也不干以数骑遁去。阔里吉思身中三矢，断其发。凯还，诏赐黄金三斤、白金千五百斤。

    成宗即位，封高唐王。西北不安，请于帝，愿往平之，再三请，帝乃许。及行，且誓曰：“若不平定西北，吾马首不南。”大德元年夏，遇敌于伯牙思之地，众谓当俟大军毕至，与战未晚，阔里吉思曰：“大丈夫报国，而待人耶!”即整众鼓躁以进，大败之，擒其将卒百数以献。诏赐世祖所服貂袭、宝鞍，及缯锦七百、介胄、戈戟、弓矢等物。

    二年秋，诸王将帅共议防边，咸曰：“敌往岁不冬出，且可休兵于境。”阔里吉思曰：“不然，今秋候骑来者甚少，所谓鸷鸟将击，必匿其形，备不可缓也。”众不以为然，阔里吉思独严兵以待之。是冬，敌兵果大至三战三克阔里吉思乘胜逐北深入险地后骑不继马踬陷敌遂为所执敌诱使降，惟正言不屈，又欲以女妻之，阔里吉思毅然田：“我帝婿也，非帝后面命，而再娶可乎！”敌不敢逼。帝尝遣其家臣阿昔思特使敌境，见于人众中，阔里吉思一见辄问两宫安否，次问嗣子何如，言未毕，左右即引其去。明日，遣使者还，不复再见，竞不屈死焉。

（节选自《元史·阔里吉思传》）

火星探测项目是我国继载人航天工程、嫦娥工程之后又一个重大太空探索项目，2018年左右我国将进行第一次火星探测．已知地球公转周期为T，到太阳的距离为R₁，运行速率为v₁，火星到太阳的距离为R₂，运行速率为v₂，太阳质量为M，引力常量为G．一个质量为m的探测器被发射到一围绕太阳的椭圆轨道上，以地球轨道上的A点为近日点，以火星轨道上的B点为远日点，如图所示．不计火星、地球对探测器的影响，则（   ）

水是最普通、最常见的物质之一．

（1）“水”有很多种，下列“水”属于纯净物的是　____ 　（填字母序号）．

A．河水　　　　　B．自来水　　　　　　C．矿泉水　　　　　　D．蒸馏水

（2）下列做法会造成水体污染的是（填字母）____ 　．

A．随意弃置废旧电池　　　　　　　　　　       B．含二氧化硫的工业废气任意排放

C．工业废水处理达标后再排放　　　　　       　D．严格监管化肥和农药的使用．

    A student's life is never easy.____A lot of preparations are needed so you can be sure to go back home with a diploma and a bright future waiting for you. The following are some basic things you need to do before seizing your passport and boarding the plane.

    Knowing the country.

    You shouldn't bother researching the country's hottest tourist spots or historical places. You won't go there as a tourist, but as a student. I'll be helpful to read the most important points in their history and to read up on their culture.____You surely don't want to face legal problems, especially if you're away from home.

    Studying their language.

    Don't expect that you can graduate abroad without knowing even the basics of the language. Before leaving your home country, take online lessons to at least master some of their words and sentences.____ Doing this will also prepare you in communicating with those who can't speak English.

    ____

    Check the conversion(兑换) of your money to their local currency, set up your bank account so you can use it there, get an insurance, and find an apartment. The Internet or your intended school will be very helpful in finding an apartment and helping you understand local currency.

    Remember, you're not only carrying your own reputation but your country's reputation as well. If you act foolishly, people there might think that all of your country men are foolish as well.____

A. Packing your clothes.

B. And it is even more difficult if you have to complete your study in a foreign land.

C. That would surely be a very bad start for your study abroad program.

D. This will be useful in living and studying there.

E. Most importantly, read about their laws.

F. Going with their trends will keep it from being too obvious that you're a foreigner.

G. Preparing for other needs.