The winds of a tornado are the most violent and destructive ones on Earth. Any of you who have seen one knows very well how frightening and powerful they are. What's interesting about them isthat scientists don't actually know exactly why tornadoes occur. We do know, however, what happens when tornadoes are formed. As you remember, a front occurs when cool, dry air from the north meets warm, humid air coming from the south(from the Gulf of Mexico, for tornadoes in the United States).Where these air masses meet, a narrow zone of storm clouds develops, and thunderstorms, and sometimes tornadoes, occur. How is this violent weather produced? Well, a mass of warm, humid air rises very rapidly. As itrises, more warm air rushes in to replace it. This inrushing air also rises, and in some cases, especially when there is extreme thermal instability, begins to rotate. When this happens, the rotating air forms a tornado. Even if you've seen tornadoes only in movies, you know that they can demolish buildings in seconds. This is possible because when a tornado passes over a house, it sucks up air from around the house and so the air pressure outside the house drops rapidly. Inside, pressure remains the same. So, air pressure inside is greater than air pressure outside. The result is that the building explodes outward. Next, we'll talk a little bit about how new technological developments are being used to try to predict tornadoes.

要继续加油啊

第十一篇
' L  I5 y: w! TAlternative fuels1 @$ T+ @  j/ o; s6 g) s# G# X9 c
chemical
7 R% U) ~4 A/ Z. E+ Q3 k% hknown as
* N& A8 g, e, D2 ?- x+ wgasoline9 C( V$ B. n, `- E
pollute# D; W. _7 z1 o# q0 h
combustion engine
" R9 i5 Y( `$ i, Hminor mechanical modification- Y; z9 }% d1 m1 z! Q/ Q& Y
antifreeze
6 Q$ h- k5 y( Q# wadded to it
. c, w! z& G) j- A0 Oundergo/undergone( i; P, g, B$ f/ s4 v
percentage
( M, q4 R2 L* n- N; hvehicle / x. b* y  b+ z( e9 d* p; ^5 Q
run on
5 z1 w, y( Z' v% x' V # R* E$ _4 ?$ ?& q1 U
第十二篇/ T, J- f6 Q% s7 b  u" f% h
Tornado: K& F5 J5 O( V; D, s. `7 S
violent
! I) m  i3 J8 P  N) p) Tdestructive* I! N. V) R3 {& ^+ J4 G
frightening and power
6 `2 R  S: @8 n! A6 L1 V* c( `occur
( c  k# M0 U- L" qhumid
3 s  b) f! M5 w9 g' p0 Y- C6 i4 egulf
, M0 {) [1 a/ ?+ v1 Oair masses
2 W- P" j, |" E% _3 ^zone& o# y, G+ |& \$ f% J
thunderstorm
- d6 [, i% S3 u) E: l: s2 lreplace
7 c; N8 p) d2 ?8 _inrushing
* j$ p  c4 N% m7 G2 ]thermal instability
; H# i$ K2 [. ~: S, ?rotate* p5 M- G* k3 ]8 \: {9 ?5 M! P
demolish
% {% F: L8 S) B7 _" Z. q* ]' Ssuck up4 J9 u! S$ p! C  M
outward/ M! M: Z# |) y" i# t% h
' E& K4 F! i8 H
; J+ p: Y/ C3 V8 n6 y! u
[ 本帖最后由 icenot 于 2008-4-18 00:18 编辑 ]

In the few minutes that remain of today's class, I'd like to discuss next week's schedule with you. Because I'm presenting a paper at a conference in Detroit on Thursday, I won't be here for either Wednesday's or Friday's class. I will, however, be here for Monday's. Next Friday, a week from today, is the midterm exam, marking the halfway point in the semester. Professor Andrews has agreed to administer the exam. In place of the usual Wednesday class, I've arranged an optional review session. Since it is optional, attendance will not be taken; however, attending the class would be a good idea for those worried about the midterm. So, remember: optional class next Wednesday; midterm, Friday.

Good afternoon. I'm here today to talk to you about a career with our airline. We're especially interested in recruiting people to fill openings for flight attendants. First of all, to work as a flight attendant with us, you must be accepted into our training program ---and with so many people applying, it's not easy to be selected. From the thousands of applications that we receive annually, we choose fewer than a thousand people for training. So, we require experience serving the public; and it also helps if you've earned some college credits. Also, not everybody who gets accepted into the training program makes it through. The course meets six days a week for five weeks.The training includes extensive classroom work in such subjects as first aid and passenger psychology as well as practical training in flight procedures and meal service. A lot of our graduates say that our fight attendants develop the skills of a nurse, a head waiter, and a public relations executive! But ,as a flight attendant myself, I can say that all of the hard work is worth it. Of course, I get to travel throughout the country, and the airline pays all of my expenses while I'm away from my base station. And, what I like best of all is that I've made friends with people from all over the country!

I need to make sure you understand how to get housing for next year. When you entered as first-year students this year, the school assigned you to a dorm and a roommate, but next year as returning students you'll choose both your roommate and your dorm. But whether or not you actually get to live in your first choice depends on what number you or your roommate draws in the lottery system. The system gives priority to the students who have been here longest. Fourth-year students get the first block of numbers, third-years get the second block, and second-years---like you'll be---get the third. The lower the number you draw, the sooner you choose. Number one gets the first choice, number two gets the second choice, and so on. You can use either your won or your intended roommate's number to make your room choice. If your roommate for next year has been at the school longer than you have, they'll be in a better block of numbers and so will have a better number than any second-year student. But most of you will probably be rooming with other second-year students and so neither of you may have a great number. You may not get into your first or even second choice. Of course, if you've made plans to live off campus, you don't need to enter the lottery at all. Dorm space will be especially tight this year because the dorms on North Campus will be closed for renovations. This means that those of you who draw the worst numbers won't be able to get dorm housing at all. In that case, the housing office will help you find off-campus housing.

占楼总结

I hope you've all finished reading the assigned chapter on insurance-so that you're prepared for our discussion today. But, before we start, I'd like to mention a few things your text doesn't go into. It's interesting to note that insurance has existed in some form for a very long time. The earliest insurance policies were called bottomry contracts. They provided shipping protection for merchants as far back as 3000 B.C. In general, the contracts were often no more than verbal agreements. They granted loans to merchants with the understanding than if a particular shipment of goods was lost at sea, the loan didn't have to be repaid. Interest on the loans varied according to how risky it was to transport the goods. During periods of heavy piracy at sea, for example, the amount of interest and the cost of the policy went up considerably. So, you can see how insurance helped encourage international trade. Even the most cautious merchants became willing to risk shipping their goods over long distances-not to mention in hazardous weather conditions-when they had this kind of protection available. Generally speaking, the basic form of an insurance policy has been pretty much the same since the Middle Ages. There are four points that were salient then and remain paramount in all policies today. There were outlined in chapter six and will serve as the basis for the rest of the of today's discussion. Can anyone tell me what one of those points might be?

Current studies show that what goes on labels is an important consideration for manufacturers, since more than seventy percent of shoppers read food labels when considering whether to buy a product. A recent controversy as to whether labels on prepared foods should educate or merely inform the consumer is over, and a consumer group got its way. The group had maintained that product labels should do more than simply list how many grams of nutrients a food contains. Their contention was that labels should also list the percentage of a day's total nutrients that the product will supply to the consumer, because this information is essential in planning a healthy diet. A government agency disagreed strongly, favoring a label that merely informs the consumer, in other words, a label that only lists the contents of the products. The agency maintained that consumers could decide for themselves if the food is nutritious and is meeting their daily needs. The consumer group, in supporting its case, had cited a survey in which shoppers were shown a food label, and were then asked if they would need more or less of a certain nutrient after eating a serving of this product. The shoppers weren't able to answer the questions easily when they were not given a specific percentage. This study, and others helped get the new regulation passed, and now food products must have the more detailed labels.

Thank you all for coming out this evening to meet sociologist Ellen Lambert. Ms. Lambert specializes in research on the workplace and recently has been writing about the future of work. This topic should be of special interest, since I know many of you are already at the forefront of workplace technology. For example, let's have a show of hands to see how many people here telecommute at least part of the time. Hmm. I see eight hands raised. Well, you eight folks who work at home and communicate with your office via computer represent one of the trends Ms. Lambert has described: that people are becoming less tied to the workplace. One of the important tools for telecommuting is electronic mail, or E-mail. E-mail lets you send and receive messages almost immediately on your computer, but you control when you read them and when you respond to them. This technology allows people to have more control over time than when relying solely on the telephone. Our guest tonight will discuss how these important changes will alter the way we work. But, before turning the floor over to Ms. Lambert, I would just like to remind you that she will be available to answer any individual questions at the reception immediately following this talk.