We’ve heard about radiation from the damaged nuclear reactors in Japan reaching American shores. Experts say so far there is no reason to worry, and point out that we meet radiation every day. Where and how? NPR’s Renee Montagne posed that question to Peter Caracappa, a radiation safety officer and professor of nuclear engineering.
MONTAGNE: How many things emit radiation?
Dr CARACAPPA: Well, radiation and radioactive material is a part of nature. So everything that’s living has some amount of radiation coming from it—a very small amout. Plus there’s radiation in the ground and the air.
So the extremes are uranium in the soil to bananas?
Yes.
By the way, why do bananas have radiation?
Bananas have a lot of potassium(钾). And a small amount of potassium naturally is called potassium 40, which is radioactive
What’s the difference between radiation that’s harmful and not harmful?
Well, the term radiation can apply to a lot of different things. But the harmful radiation is ionizing(离子)radiation. It has enough energy that it can make chemical changes in material. We could get ionizing radiation from an X-ray, for example. It’s the kind of radiation that causes cancer.
The broader definition of radiation includes a lot of things that we call non-ionizing radiation. That includes everything like radio waves and visible light and your microwave.
So what then is the largest contributor of ionizing radiation?
For the natural sources of ionizing radiation, actually the biggest chunk of that tends to come from radon(氡), which is a radioactive material that is present in the air. It can become a concern when it builds up in low-lying areas of homes like basements.
Would it be fair to say that most people do not need to worry about the danger of being exposed to radiation?
I would say that the everyday exposure to radioation that we meet contributes an extremely tiny risk to our life or to our health compared to all of the other risks that we meet in our day-to-day life.We can infer from the first paragraph that radiation is______.
| A．rare | B．powerful | C．dangerous | D．common |
The passage may be _______.
| A．an interview | B．an argument | C．a talk show program | D．a science report |
Whether radiation is harmful or not depends on______.
| A．whether it has a small amount of potassium |
| B．whether it changes chemical in materials. |
| C．whether it has energy to change materials |
| D．whether it is visible in life |
The purpose of writing this passage is to _______.
| A．advise on how to protect us from radiation |
| B．analyze what causes radiation in daily life |
| C．warn people of the danger of radiation |
| D．expect people not to fear everyday radiation |
I give two examples as to why intelligent life may not actually exist, though I admit that for me, or even for a physicist who devoted his or her entire life to researching and studying the universe, it's shocking to claim that completely no life exists elsewhere.
Keeping that in mind, I'd just like to consider conditions elsewhere in the known universe. You really only need to look at our own solar system or the Earth at certain periods in its own history to appreciate that most places are much worse and much less suitable for life than our mild, watery globe.
So far, space scientists have discovered about seventy planets outside the solar. But it appears that if you wish to have a planet suitable for life, you just have to be very lucky, and the more advanced the life is, the luckier you'll have to be. I'm by no means a space observer, but I can recognize some particularly fortunate breaks we've had on the Earth. For example:
We are, to a degree, at the right distance from the perfect type of star, the one that is big enough to radiate a huge amount of energy, but not so big as to bum itself out quickly. Had our sun been ten times as huge, it would have burnt out completely after only ten million years, instead of ten billion and surely we would not exist. Too near, everything on the Earth would have boiled and withered away; any further, everything would have frozen over.
The universe is a surprising place, and our existence within it is a wonder. If a long and unimaginably complex sequence of events dating back 4.6 billion years or so hadn't happened in a particular manner at a particular time --if, to take just one example, the dinosaurs hadn't been wiped out by a meteor(流星)--we might still be a few centimeters long, with whisker(胡须) and a tail, and you'll be reading this in a cave somewhere.What's the best title for this passage?
| A．No Life Exists out of the Earth |
| B．Seventy Planets Discovered |
| C．A Place Full of Wonders |
| D．Perfect Conditions for Life |
What makes the Earth more suitable for life than other planets in the solar system?
| A．The Earth is the only planet that can receive energy from the sun. |
| B．The sun is at the right distance from us and in proper size. |
| C．The distance between the planets was neither too long nor too near. |
| D．The dinosaurs were no longer a threat to the Earth. |
What does the underlined phrase "withered away" in the 4th paragraph mean?
| A．Exploded. | B．Expanded. | C．Floated away. | D．Dried and died. |
Where does the text probably come from?
| A．A history book. | B．A magazine. | C．A science fiction. | D．A famous novel. |
WELLINGTON, September 19 (Xinhua) -- If your teenage son won't get out of bed in the morning, then take comfort from the fact that he might be sleeping his way to a healthier future, according to a new research from New Zealand.
Researchers in human nutrition at the University of Otago have found that teenage boys who sleep less have more body fat when compared to girls, for whom lack of sleep has no noticeable effect on their body fat ratios.
The study of 386 boys and 299 girls aged 15 to 18 found that average-sized 16-year-old boy weighing 69.5 kg and 176 cm tall, who slept for eight hours a day, had a waist size l.8 cm bigger and l.6 kg, or 9 percent, more body fat than the average-sized boy who slept 10 hours a day.
"The boys who slept eight hours a day would also have l.8 kg more lean (bone and muscle) mass compared to the boys who slept 10 hours, but that's only a 1.4-percent increase, compared to the 9- percent increase seen in body fat," said lead researcher from the Department of Human Nutrition, Dr. Paula Skidmore.
"Our results suggest that for older teenage boys, making sure that they get enough sleep may help to maintain a healthier body. It seems to be that, within reason, the more sleep the better for boys," Skidmore said in a statement Thursday.
"It was unexpected that we did not find the same result in girls, who may actually be more aware of their diet and more in tune with a healthier lifestyle."
The researchers ruled out the effects of food choice and number of screens, such as televisions, games and consoles, which the teenagers had in their bedrooms.What's the research really about?
| A．Boys and girls. | B．Food and weight. | C．Sleep and health. | D．Screens and fat. |
What's the result of less sleep for teenage boys?
| A．Bigger waist and more fat in the body. |
| B．An increase in weight and height. |
| C．More concerned with their diet. |
| D．A decrease in bone and muscle. |
From the sixth paragraph we can infer that ______.
| A．girls usually sleep less and have healthier lifestyles than boys |
| B．the researchers expected to see the same result in girls |
| C．peoples' diet has a great effect on their health |
| D．boys are usually lazier than girls |
Who would be the most pleased to hear the news?
| A．Teachers. | B．Girls. | C．Parents. . | D．Boys. |
Back in old times, people had little knowledge about the universe and nature. Things we now consider to be common sense were mysteries to our ancestors.
Over the years, major breakthroughs have been made in science and many phenomena have been explained. But still, there are always questions we can't yet answer, and The Guardian has listed some of them.
1. What makes us human?
Just looking at your DNA won't tell you - human DNA is 99 percent identical to that of the chimpanzee and, believe it or not, 50 percent identical to a banana's! A lot of the things we once thought were unique about us - language and tool use, recognizing ourselves in the mirror and so on – have since been seen in other animals. Perhaps it's our culture that makes the difference or maybe our ability to use fire. It's also possible that our capacity (能力) for co-operation and our trading skills are what make us unique.
2. Why do we dream?
Given the fact that we spend around a third of our lives sleeping, shouldn't we know everything about it? Unfortunately, scientists are still searching for a complete explanation of what happens when we sleep and why we dream.
Austrian psychologist Sigmund Freud believed dreams were the expressions of wishes that we can't fulfill in our real lives. Others have wondered whether dreams are just random "noise" coming from a sleeping brain.
3. Could we someday live forever?
Apart from accidents, most people die because of diseases that can be treated and aging. And since many diseases, such as diabetes（糖尿病） and cancer, are diseases of aging, treating aging itself could be the key to extending our lives.
Our knowledge of what causes us to age - and what allows some animals to live longer than others - is expanding rapidly. And though we haven't quite worked out all the details, we've worked out some pieces of the puzzles such as DNA damage and metabolism (新陈代谢), which are all leading to the invention of drugs that can slow down the aging process.
If we're lucky enough to lengthen our lives, we might even get to see the day when all of these questions are answered.The main point of the passage is ______.
| A．to inform people of the knowledge about the universe and nature |
| B．to introduce major breakthroughs that have been made in science |
| C．to present some questions we can't yet answer |
| D．to explain what were once mysteries to our ancestors |
Chimpanzees and bananas are mentioned as examples to prove that ______.
| A．human beings are actually not different from other animals |
| B．animals have completely different DNA from that of plants |
| C．both animals and plants share the same amount of DNA |
| D．DNA alone is not good enough to make humans different |
The underlined word "identical" is closest in meaning to ______.
| A．mysterious | B．unique | C．advanced | D．same |
Which of the following statements is TRUE according to the passage?
| A．What were mysteries to our ancestors are considered to be common sense now. |
| B．Now we know much more about dreams than our ancestors did in the past. |
| C．With the invention of new drugs people can possibly live even longer. |
| D．If all the diseases can be treated people can theoretically live forever. |
One day, when I was a freshman in high school, I saw Kyle from my class walking home from school. It looked like he was carrying all of his books. I thought to myself, "Why would anyone bring home all his books on a Friday? He must really be a nerd (a foolish person)." I had quite a weekend planned, so I shrugged my shoulders and went on.
As I was walking, I saw a bunch of kids running towards him. They knocked all his books out of his arms and tripped(绊倒) him so he landed in the dirt. His glasses went flying, and I saw them land in the glass about ten feet from him. He looked up and I saw this terrible sadness in his eyes. So, I jogged over to him and as he crawled around looking for his glasses, I saw a tear in his eye.
As I handed him his glasses, I said, "Those guys are jerks. They really should go to hell." He looked at me and said, "Hey, thanks!" There was a big smile on his face. It was one of those smiles that showed real thankfulness. I asked him where he lived. As it turned out, he lived near me.
Over the next four years, Kyle and I became best friends. I teased him all the time about being a nerd. He had to prepare a speech for graduation. As he started his speech, he cleared his throat, and began. "Graduation is a time to thank those who helped you make it through those tough years. I am here to tell you a story."
I just looked at my friend with disbelief as he told the story of the first day we met. He had planned to kill himself over the weekend. He talked of how he had cleaned out his locker so his Mom wouldn't have to do it later and was carrying his stuff home. He looked hard at me and gave me a little smile. "Thankfully, I was saved. My friend saved me from doing the unspeakable."
I heard the gasp(倒吸气) go through the crowd as this handsome, popular boy told us all about his weakest moment. I saw his Mom and Dad looking at me and smiling that same grateful smile. Not until that moment did I realize its depth.Why did Kyle carry all his books home?
| A．Because it was Friday. |
| B．Because he was a nerd. |
| C．Because he wanted to kill himself. |
| D．Because he liked doing things for his mother. |
Which of the statements is TRUE according to the passage?
| A．The bunch of kids attacked Kyle to have his glasses and books. |
| B．The author planned to study all weekend after he met Kyle. |
| C．The author was a freshman when Kyle gave the speech. |
| D．Kyle felt grateful to the author for his help. |
What can we infer from the passage?
| A．When Kyle couldn't find the glass, he turned to the author for help. |
| B．The author teased Kyle a lot about being a nerd. |
| C．The author didn't expect Kyle to tell the story. |
| D．Kyle thanked his parents first for saving his life. |
What does the underlined "them" in the 2nd paragraph refer to?
| A．The kids. | B．Kyle's books. | C．Kyle's glasses. | D．Kyle's arms. |
Hours & Admission
Open Daily 10:00 a.m. - 5:00 p.m. except major holidays (see below)
July and August only - Thursdays until 7:00 p.m.
Please Note: all MIT Museum sites are wheelchair accessible.
Admission beginning July l, 2013
Adults: $10.00; youth under 18, students, seniors: $5:00; children under age 5: free
Admission is free the last Sunday of each month, all day, from September 2013 -June 2014
Evening programs are free with Museum Admission
Visit our Partner Organizations pages for more information about discounts(折扣).
Closed, 2013:
January l: New Year's Day
May 27: Memorial Day
July 4: Independence Day
September 2: Labor Day
November 28: Thanksgiving Day
December 24 & 25: Christmas Eve & Christmas Day
December 31: Early Closing for New Year's DayThe information you read above is probably about ______.
| A．a museum | B．a cinema | C．a park | D．a cafe |
How much do they have to pay in total if a family, including grandparents, parents and a child of 8, go together on the last Sunday of November 2013?
| A．$0. | B．$25. | C．$30. | D．$35. |
You won't be refused at the door if you go there at ______.
| A．Thanksgiving Day | B．Christmas Day |
| C．6 p.m. on a Thursday of July | D．6 p.m. on a Tuesday of August |
Which of the following statements is TRUE?
| A．Children under the age of 7 do not have to pay. |
| B．It is possible for the disabled to go there on wheelchairs. |
| C．Visitors have to pay some extra money for the evening programs. |
| D．There are definitely no more discounts besides those listed here. |
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