Radar is an electronic device that detects planes，ships，coastlines，landmarks，and even storm clouds．The name radar comes from the first letters of the words radio direction and ranging．As the human eye uses light waves to see，radar "sees" with radio waves．Without radar，planes could not land safely in bad weather and ships could not move safely in thick fog．（1）DD
In the 1800s it was discovered that radio waves could be reflected from objects．But scientists did not make great advances in radar research until the 1930s，when the world was threatened by war．（2）EE It has been used widely in almost every conflict since then．
Echoes make it possible for radar to work．When a beam of radio waves is sent out，it strikes on an object and returns an echo．This echo is picked up by radar and recorded on a screen similar to television screen．On the screen an observer sees a flash，or a blip，that shows the direction and distance of the object．（3）BB
Airport control towers use radar to guide planes in for safe landings．Almost all large ships depend on radar to prevent collisions with icebergs or other ships．（4）AAWeather forecasters "see" the size，direction，and speed of storms on radar screens．Astronomers can even use radar to measure accurately the distance to the moon．Thus，the device has generated major advancements．
（5）GGHuge radar antennas have been installed all over the United States．They guard us against possible enemy attacks．We have ballistic-missiles （戰(zhàn)略導(dǎo)彈）warning systems that can alert us to attacks when missiles are more than 1，000 miles away．Other radar systems warn us against enemy aircraft and even spying space satellites．
A．Police track speeders in radar-equipped cars．
B．These measurements are now highly accurate．
C．The device can be used in a wide range of fields．
D．It is therefore especially valuable to shippers and travelers．
E．During World War II many countries used radar effectively．
F．Today radar is used by commercial airliners and weather forecasters．
G．Strengthening national defense is one of radar's most important functions．
【考點】人與自我．
【答案】D；E；B；A；G
【解答】
【點評】
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發(fā)布：2024/4/20 14:35:0組卷：17引用：7難度：0.5
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So make sure you're permitted to use an app or service，and pay attention to how you are using it．Here're some important points you may find helpful．
Choose what's best for you．Some location-sharing services are games that let you give a shout-out when you've turned up at a particular spot．（2）Still others continue to share your location until you change the setting．Be sure you know exactly how your service shares your location．
Know who your friends are．（3）This means people can search to see if you're online and add you as a friend．It's important to remember that sharing your location with people you've never met in real life is risky，so you should carefully manage friend requests and share your location only with people you know and trust．
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Update parents．Location-based services are a great way for teens to let parents know where they are without having to call or text．（5）If you're heading home late at night，you can also use a service like Glympse to share your location as you drive，so they'll know if you have car trouble or get stuck in traffic．A．Check back often．
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G．Some location services operate like Facebook，where you invite and accept friends．發(fā)布：2025/1/1 18:0:1組卷：7引用：4難度：0.7 -
2．"Me".It's a small word with big meaning，and that meaning is as individual to each of us as the way we look.Through interviews，Dr Hart，a psychologist，was able to discover what "me" means to other people，and how they have learnt to（1 ）
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3．Dear Laura，
Thanks for letting us to stay at your seaside house． Now， you might have heard from your neighbors about which happened on Saturday evening． When I was out a walk， my younger son， Tom， played football before your house． He made so many noise that the neighbors got quite angrily． Even worse， Tom broke one of the window of Mr． Wilson's house． Tom and I apologized to all the neighbors for the unhappy happenings， but promised to have the broken window repair soon． Tom said that we would not do such silly things any more． I am glad that your neighbors had forgiven us． They are really nice people．
Yours，
Betty發(fā)布：2025/1/30 8:0:1組卷：12引用：2難度：0.5