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A sandstorm, also known as a dust storm, is exactly what it sounds like. A very strong windstorm especially in the desert carries clouds of sand or dust that greatly reduces visibility. This wind is usually caused by convection currents (对流气流), which are created by intense heating of the ground, and is usually strong enough to move entire sand dunes. Air is unstable when heated, and this instability in the air will cause higher winds to mix with winds in the lower atmosphere, producing strong surface winds.
Sandstorms can disturb people’s travel, and can sometimes destroy whole roads, and dry flat areas. Similar dust storms can be found on the planet Mars, and are thought to be seasonal. Today, the destruction of forests and too much farming of farmland can lead to sandstorms. Too much use of water resources can also cause sandstorms.
In the United States of America, sandstorms are rare because of the lack of large deserts and more importantly the development of proper agricultural techniques. The last recorded destructive sandstorm in American history was the Dust Bowl, which occurred on July 16, 1971 and was widely recorded by meteorologists (气象学家).
To protect themselves from sandstorms, some people wear protective suits. Special equipment can be fixed in some cars to prevent sand from getting into the engine. Sandstorms can cause coughs, and the sand and dust has also been known to carry “infectious diseases”. Sand particles, unlike dust ones, will block air passages, and cause a person who breathes them in to choke. Dust particles may cause an allergic (过敏的) reaction.
1.Which of the following plays the first part in forming sandstorms?
A．The instability of the sand.
B．The instability of the wind.
C．The intense heating of the ground.
D．The speed of the wind.
2.From the second paragraph, we can learn that at present _______.
A．sandstorms are more often seen on Mars than on Earth
B．sandstorms have led to the lack of clean water resources
C．farming brings more harm than benefits to humans
D．human activities are a major cause of sandstorms
3.The author will most probably agree that ________.
A．there will soon be no sandstorms in the USA
B．humans haven’t thought of any way to deal with sandstorms
C．death caused by sandstorms is increasing all the time
D．humans should make more efforts to stop soil turning into desert
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There are many places around the city and online to buy Las Vegas show tickets. With dozens of websites you can find at home, ticket box offices, Tix 4 Tonight (one of the two half-price ticket sellers) locations, and ticket sellers along the Las Vegas trip, you might wonder where you could find your best deal.
Major Shows
If you want to see one of the top shows in Las Vegas, you could buy your tickets online before your trip. Many of these shows sell out months ahead of time, so make sure you do your research.
Best Place to Buy Discounted (打折的) Tickets
If you want discounted tickets for Las Vegas shows, you should go to one of the four Tix 4 Tonight locations. These locations get tickets early in the morning or throughout the day if shows are not sold out. Do not expect to find discounted tickets here for the hottest shows in town such as one-night concerts or shows like Celine Dion’s. These seldom make their way to Tix 4 Tonight.
Coupon books (代金劵)
As you walk along the Las Vegas Strip, you are going to come across people handing out the Vegas Values coupon books or other coupons. These may help you find discounted coupons for various shows around town. Tickets bought with coupons have to be bought at the box office for the show. These are usually located near the theater used for the show.
On-Strip Sellers
If you see people standing on the Strip selling show tickets, make sure you avoid them. While a few of these sellers might be legitimate (合法的)，they often cheat people by selling counterfeit (伪造的) tickets.
Catching a show in Las Vegas is one of the various activities people take part in every single day. While there is not one set place to be the best to buy tickets, make sure you get to see the show you want.
1.If you want to see Celine Dion’s performance, you should buy the tickets __ _____.
A．from the tickets sellers along the Strip
B．through online shopping
C．at the Tix 4 Tonight locations
D．on the day of the performance
2.What’s the author’s purpose in writing this text?
A．To introduce various Las Vegas shows.
B．To introduce the interesting places in Las Vegas.
C．To tell people the ways of getting Las Vegas show tickets.
D．To tell people the advantage of getting tickets online.
3.In which part of a newspaper could we find the text?
A．Business. B．News. C．Travel. D．Sports.
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There are two factors which determine an individual's intelligence. The first is the sort of brain he is born with. Human brains differ considerably, some being more capable than others. But no matter how good a brain he has to begin with, an individual will have a low order of intelligence unless he has opportunities to learn. So the second factor is what happens to the individual—the sort of environment in which he is reared (培养). If an individual is handicapped (妨碍) environmentally, it is likely that his brain will fail to develop and he will never attain the level of intelligence of which he is capable.
The importance of environment in determining an individual's intelligence can be demonstrated by the case history of the identical twins, Peter and Mark X. Being identical, the twins had identical brains at birth, and their growth processes were the same. When the twins were three months old, their parents died, and they were placed in separate foster homes. Peter was reared by parents of low intelligence in an isolated community with poor educational opportunities. Mark was reared in the home of well-to-do parents who had been to college. He was read to as a child, sent to good schools, and given every opportunity to be stimulated intellectually. This environmental difference continued until the twins were in their late teens, when they were given tests to measure their intelligence. Mark's I.Q. was 125, twenty-five points higher than the average and fully forty points higher than his identical brother. Given equal opportunities, the twins, having identical brains, would have tested at roughly the same level.
1.This passage can be best titled_________.
A．Intelligence and Environment
B．Measuring Your Intelligence
C．The Case of Peter and Mark
D．How the brain Influences Intelligence
2.According to the passage, the average I.Q. is _____.
A．85 B．125 C．110 D．100
3.The case history of the twins appears to support the conclusion that _______.
A．individual with identical brains seldom test at same level
B．an individual's intelligence is determined only by his environment
C．changes of environment produce changes in the structure of the brain
D．lack of opportunity blocks the growth of intelligence
4.This passage suggests that an individual's I.Q.______.
A．can be increased by education
B．stays the same throughout his life
C．can be predicted at birth
D．is determined by his childhood
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删除：把多余的词作斜线（\）划掉。