题目内容

Flickering lights are annoying but they may have an advantage. Visible light communication (VLC) uses rapid pluses of light to transmit information wirelessly. Now it may be ready to compete with conventional Wi-fi.

In a recent TED talk, Harald Hasas from the University of Edinburge,UK demonstrated one VLC prototype(原型），“Li-Fi", transmitting a video from a store-bought LED lamp to a solar cell to a laptop. “Li-Fi is essentially the same as Wi-Fi,except for a small difference- we use LED lights around us to transmit the data wirelessly as opposed to using radio," Haas says.

Once established, VLC could solve some major communication problems. In 2009, the US Federal Communications Commission(FCC) warned of spectrum (波谱）crisis: because our mobile devices are so data- hungry we will soon run out of radio-frequency bandwidth.Li-Fi could free up bandwidth, especially as much of the infrastructure is already in place."There are around14 billion light bulbs worldwide, they just need to replaced with LED ones that transmit data", says Haas.

The idea of transmitting data through the visible light spectrum is not new.Alexander Graham Bell transmitted sound via a beam of sunlight in 1880 using a photo phone, a sort of solar-powered wireless telephone. In the past several decades, a number of researchers have looked at using visible light to transmit data.

But what Haas seized on is the use of simple LED light bulbs for data transmission. LED bulbs are controlled by a driver, which can rapidly di the light or turn it on or off. Therefore, Haas figured, data could be encoded in subtle shifts of the light’s brightness. Eventually, he creaded a working transmitter and receiver system with an IKEA lamp and a solar panel.

Li-Fi stands to be much faster than Wi-Fi. According to Haas research, Li-Fi can achieve data density 1000 times greater than Wi-Fi,because Li-Fi signals are contained in a small area, as opposed to the more diffuse (分散的)，radio signals.The system wouldn’t mean having to keep your lights on all the time either, Haas says---bulbs could be dimmed to such a point that they appear off, but still transmit data.

Now, Haas’ team hopes that Li-Fi could make its way into homes in a few years. The system can easily network any device with an LED light—an electric kettle, an oven. Eventually, this could bring about the Internet of Things era much faster. Haas also sees Li-Fi as a way to bring internet to remote location, using hilltop transmitters and rooftop solar panels. LED streetlights could even be used to form a network of outdoor Li-Fi, making it possible to stay connected when walking around the city.

But some sound a cautious note about VLC’s future. It becomes less powerful , for example,when light is blocked, wheather due to fog or other conditions.

1.By saying "There are around14 billion light bulbs worldwide”Haas intended to tell us that ______________

A. mobile devices will consume more data

B. radio-frequency bandwidth needs to be freed up.

C. VLC might solve the spectum crisis.

D. the world has a complete lighting infrastructure.

2.The underlined phrased “seized on“ in the passage is closet in meaning to “_____________”

A distinguished B. exploited C. created D. figured

3.We can learn from the passage that ________________________

A. Li-Fi can’t work outdoors.

B Li-Fi can work with LED lights off.

C. Li-Fi can be used with all household appliances.

D. Li-Fi needs improving to next diverse need.

练习册系列答案
相关题目

短文改错

假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下作文。文中共有10处语言错误，每句中最多有两处，每处错误仅涉及一个单词的增加、删除或修改。

增加：在缺词处加一个漏字符号（∧），并在其下面写出该加的词。

删除：把多余的词用斜线（\）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1.每处错误及其修改均限一词。

2.只允许修改10处，多者（从第11处起）不计分.

Yesterday morning, I was surprising to hear that my best friend Allee has been hit by a car and was in hospital. The other day when he was going to cross a street,he was such careful that he didn’t go until he saw the traffic light to turn green. But hardly had he got to the middle of the street while he saw a car suddenly appear on his right-hand side and come directly towards them. It was too late for Allee to escape. He was hit by the car or was thrown a few meters away. He was sent to the nearest hospital immediately and had operation. When I went to see him, he was out of dangers but still looked pale. I sincere hope he will recover and return to normal as soon as possible.

阅读下面材料，在空白处填入适当的内容（不多于3个单词）或括号内单词的正确形式。

An old proverb says, “Friends are like wine; the older, the better.” So, nowadays many people consider old friends to be 1. (important) than new friends. For example, if two pieces of advice 2. (give) to solve a problem, one from a new friend and the other from 3. old friend, people always tend to 4. (adoption) the latter one, although the new friend's advice may be better.

5. (disagree) with the old proverb, I believe that new friends are not 6. (necessary) worse than old friends. Why? Because the length of time cannot determine whether your friendship is better or not.

Once you call someone friend, he must be a person who is 7. (rely) and whose interests are in common with 8. (you). As time goes by, a friend's outside look may change, but the inside characters of him and his interests 9. (change).It is just these unchangeable characters and interests 10. make him a friend to you. Therefore, on this point, there is no difference between old friends and new friends.

短文改错

假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下短文。

短文中共有10处错误，每句中最多有两处。错误涉及一个单词的增加、删除或修改。

增加：在缺词处加一个漏词符号∧，并在此符号下面写出该加的词。

删除：把多余的词用斜线＼划掉。

修改：在错词下面划一横线，并在该词下面写出修改后的词。

注意：1、每处错误及其修改均仅限一词；

2、只允许修改10处，多者（从第11处起）不计分。

Last weekend I visited my best friend in London, which was supposed to be excited. Melina, whom I have not seen for three years, offered to take me on a sighting tour by car. Unfortunate, she ended up doing everything but that! First, she showed me around the building where she had gotten her first job. Then she drove me to the café where she had met first boyfriend . Before I could say everything, she smiled at me and said she wanted to take me to another place where was special to her. I was very disappointed when we got on the place where she had bought her car! Besides, she kept talk about herself all day long! I was fed up with it, but I couldn’t make her to stop. When she finally decides to call it a day, she turned around and found me asleep!

Every Wednesday, I go to Cantata Adult Life Services, a local retirement community in Brookfield, Illinois, US, with my classmates to do community service.

After my very first visit to Cantata, my life changed forever. That may sound a bit dramatic, but volunteering with the elderly has changed my views on life.

Our visits last about an hour, and we bring 25-30 students every time. We play board games and cards with the residents while we’re there.

You can watch all the movies and TV shows you want about “life back then”, but nothing compares to talking to the people who were actually there. Just hearing their stories has touched me in a way I never thought possible.

Whether it was talking to 98-year-old “Hurricane Hilda” about her glory days as a roller skater or chatting with Lou about the times she danced with a famous actor, I was completely attracted by every single memory the residents wanted to share with me.

Even the residents who don’t have amazing memories make the experience satisfying . I remember visiting Mrs Robinson. She couldn’t recall much about her past, but she told me she’d never forget how kind I was just to listen to her “rambling (漫谈)”. It made me realize that it’s the little things that make life worth living. That’s something I won’t forget anytime soon.

If there’s one thing I’ve realized in my three years of visiting Cantata, it’s that presence – just being there – means more than anything to many of the residents. And despite how busy our lives are, there’s always time to make someone’s day.

For me, it feels great to be a source of happiness, a smile on a bad day or a listening ear for old memories. And at the end of the day, that’s all that matters.

It’s easy to feel like you don’t have anything in common with the elderly – especially when you’re a teenager. But that’s not true at all.

I hate to be overly clichéd (陈词滥调的) here, but age really is just a number. As young adults, it’s important for us to realize this sooner rather than later. We can learn a lot from the elderly, and they can often benefit from teenagers too.

1.What do the volunteers do according to the passage?

A. They share everything with the residents.

B. They play board games and cards with the residents.

C. They watch the residents play games.

D. They buy gifts for the residents.

2.According to the writer, what is the most important thing that volunteers can do for the elderly?

A. Playing with them. B. Benefiting from them.

C. Helping them. D. Being there with them.

3. What does the writer want to tell us by writing this passage ?

A. We don’t have anything in common with the elderly.

B. Age is just a number.

C. It is important to help the elderly.

D. Young adults and the elderly can benefit from each other.

Much time _____ siting at a desk, office clerks are generally troubled by various health problems.

A. being spent B. having spent

C. spending D. spent

Despite her recent surgery she has been carrying on ________.

A. consequently B. otherwise C. likewise D. regardless

TV Affects dreams

We have dreams almost every night. Do you ever notice the colors of your dreams? Do you dream in black and white or do you dream in yellow, red and green?

New research suggests that the type of television you watched as a child has a great effect on the color of your dreams.

While almost all people under 25 dream in color, thousands of people over 55, all of whom were brought up with black and white TV sets, often dream in monochrome(黑白画面)。

“It suggests there could be a critical period in our childhood when watching films has a big impact on the way dreams are formed”, said Eva Murzyn, a psychology student at Dundee University in Britain who carried out the study.

Research from 1915 through the 1950s suggested that the vast majority of dreams are in black and white. But the tide(潮流) turned in the sixties, and later results suggested that up to 83 percent of dreams contain some color.

Since this period also marked the transition(过渡) between black-and-white film and TV and Technicolor(印染法彩色)，an obvious explanation was that the media had been painting people’s dreams. However, there weren’t any firm conclusions.

But now Miss Murzyn believes she has proven the link. She made a survey of more than 60 people, half of whom were over 55 and half of whom were under 25.

She asked the volunteers to answer a questionnaire on the color of their dreams and their childhood exposure to film and TV.

She then analyzed her own data. Only 4.4 percent of the under-25s’ dreams were black and white. The over-55s who had had access to color TV and film during their childhood also reported a very low proportion of just 7.3 percent.

But the over-55s who only had access to black-and –white media reported dreaming in black and white about a quarter of the time.

Even though they would have spent only a few hours a day watching TV or films, their attention and emotion would have been heightened during this time, leaving a deeper imprint on their mind, Miss Murzyn told the New Scientist.

“The crucial time is between three and ten when we all begin to have the ability to dream”, she said.

1.What’s the main idea of the passage?

A. The relationship between dream color and types of television and films people watch.

B. The relationship between dreams and types of television and films that people watch.

C. The relationship between people’s dreams and colors that they see in their life.

D. The relationship between dream color and the age of the people.

2.From the text, we can see that ___________.

A. all people who are below 25 dream in color

B. watching TV or films probably affects dream color

C. people over 55 always dream in monochrome

D. people begin to dream when they are 10 years old

3. Which is WRONG according to the passage?

A. Miss Murzyn thought she has proved the connection between dream color and TV and films.

B. The 1960s was a time which marked a transition in dream color.

C. The period between 3 and 10 is an important time in forming dreams.

D. Eva Murzyn is a professor at Dundee University in Britain.

4.In which magazine can you find the article?

A. Aging Healthily B. Psychology Analysis

C. New Scientist D. TV And Film Reviews

Brad closed the door slowly as Sue left home to visit her mother. Expecting a whole day to relax, he was thinking whether to read the newspaper or watch his favorite TV talk show on his first day off in months. “This will be quite easy, just like a walk in the park,” he’d told his wife. “I’ll look after the kids well, and you can go to visit your mom.”

Things started well, but just after eight o’clock, his three little “good kids”—Mike, Randy, and Alex—came down the stairs in their night clothes and shouted “Breakfast, Daddy.” When food had not appeared within thirty seconds, Randy began using his spoon on Alex’s head as if it were a drum (鼓). Alex started to shout loudly in time to the beat (节拍). Mike chanted (咏唱) “Where’s my toast, where’s my toast” in the background. Brad realized his newspaper would have to wait for a few seconds.

Life became worse after breakfast. Mike wore Randy’s underwear on his head. Randy locked himself in the bathroom, while Alex shouted again because he was going to wet his pants. Nobody could find clean socks, although they were just before their eyes. Someone named “Not Me” had spilled a whole glass of orange juice into the basket of clean clothes. Brad knew the talk show had already started.

By ten o’clock, things were out of control. Alex was wondering why the fish in the jar refused his bread and butter. Mike was trying to show off his talent by decorating the kitchen wall with his color pencils. Randy, thankfully, appeared to be reading quietly in the family room, but closer examination showed that he was eating apple jam straight from the bottle with his hands. Brad realized that the talk show was over and reading would be impossible.

At exactly 11:17, Brad called the daycare centre. “I suddenly have to go into work and my wife is away. Can I bring the boys over in a few minutes?” The answer was obviously “yes” because Brad was smiling.

1.When his wife left home, Brad expected to __________.

A. go out for a walk in the park

B. watch TV talk show with his children

C. read the newspaper to his children

D. enjoy his first day off work

2.Who spilled orange juice into the basket of clean clothes?

A. One of the boys. B. Brad himself.

C. Brad’s friend. D. Brad’s wife.

3.Why did Brad ask the daycare centre for help?

A. Because he wanted to play with his friends.

B. Because he found it hard to manage his boys home.

C. Because his boss asked him to work.

D. Because he had to take his wife back.

4.This passage is developed __________.

A. by space B. by result C. by time D. by cause

违法和不良信息举报电话：027-86699610 举报邮箱：58377363@163.com

精英家教网