Drinking eight cups or two litres of water a day is longstanding advice. But is there any scientific basis for it, asks Dr Chris van Tulleken.
You know those ads that remind us that even a small drop in hydration（水合作用） levels can massively affect performance so you need to keep hydrated with whatever brand of super drink they're selling?
They seem pretty scientific don't they? Man in white coat, athlete with electrodes attached and so on. And it's not a hard sell because drinking feels right - you're hot and sweating so surely replacing that fluid must be beneficial.
Well earlier this year sports scientists in Australia did an extraordinary experiment that had never been done before.This group wanted to find out what happened to performance after dehydration. So they took a group of cyclists and exercised them until they lost 3% of their total body weight in sweat.
Then their performance was assessed after rehydration with either 1) nothing, 2) enough water to bring them back to 2% dehydration or 3) after full rehydration.
So far nothing unusual, but the difference between this and almost every other study that's ever been done on hydration was that the cyclists were blind to how much water they got. The fluid was given intravenously without them knowing the volume.
This is vital because we all, and especially athletes, have such an intimate(密切的)psychological relationship with water consumption.
Remarkably, there was no performance difference between those that were fully rehydrated and those that got nothing. This study was part of a growing movement to "drink to thirst" which hopes to persuade athletes not to over hydrate with the potentially fatal consequence of diluting your sodium level, causing hyponatraemia.
Perhaps the result shouldn't be so surprising. Humans evolved doing intense exercise in extreme heat and dryness. We are able to tolerate losses in water relatively well whereas even slight over hydration can be far more dangerous. In simple terms, being too watery is as bad for you as being too concentrated. What’s the main idea of the passage?
| A．There is no scientific basis for drinking eight cups of water a day |
| B．People used to drink eight cups of water a day |
| C．An experiment about whether people should drink eight cups of water. |
| D．People shouldn’t believe longstanding advice. |
what does the word“dehydration ”in paragragh 4 mean？
| A．doing exercise | B．losing water |
| C．drinking water | D．having a rest |
What is NOT TRUE according to the passage?
| A．Drinking too much water is bad for us |
| B．Sports scientists in Australia did an extraordinary experiment for the first time. |
| C．Those that were fully rehydrated and those that got nothing performed differently. |
| D．The cyclists didn’t know how much water they got. |
What can we learn from the last paragragh?
| A．Humans can bear losing water relatively well |
| B．It’s dangerous to drink water. |
| C．Athletes should drink more water than others. |
| D．This study was part of a growing movement to "drink to thirst". |
what is Dr Chris van Tulleken’s attitude towards the. longstanding advice？
| A．positive | B．doubtful | C．supportive | D．indifferent |
Twenty years ago, I drove a taxi for a living. One night I went to pick up a passenger at 2:30 AM. When I arrived to collect, I found the building was dark except for a single light in a ground floor window.
I walked to the door and knocked. “Just a minute.” answered a weak, elderly voice. After a long pause, the door opened. A small woman in her eighties stood before me. By her side was a small suitcase. I took the suitcase to the car, and then returned to help the woman. She took my arm and we walked slowly toward the car. She kept thanking me for my kindness. “It’s nothing,” I told her. “I just try to treat my passengers the way I would want my mother treated.”
“Oh, you’re such a good man,” she said. When we got into the taxi, she gave me an address, and then asked, “Could you drive through downtown?”
“It’s not the shortest way.” I answered quickly.
“Oh, I’m in no hurry.” she said. “I’m on my way to a hospice（临终医院）. I don’t have any family left. The doctor says I don’t have very long.”
I quietly reached over and shut off the meter（计价器）. For the next two hours, we drove through the city. She showed me the building where she had once worked, the neighborhood where she had lived, and the furniture shop that had once been a ballroom where she had gone dancing as a girl. Sometimes she’d ask me to slow down in front of a particular building and would sit staring into the darkness, saying nothing. At dawn, she suddenly said, “I’m tired. Let’s go now.” We drove in silence to the address she had given me.
“How much do I owe you?” she asked.
“Nothing,” I said.
“You have to make a living.” she answered. “Oh, there are other passengers,” I answered.
Almost without thinking, I bent and gave her a hug. She held onto me tightly. Our hug ended with her remark. “You gave an old woman a little moment of joy.” The old woman chose to ride through the city in order to.
| A．show she was familiar with the city |
| B．see some places for the last time |
| C．let the driver earn more money |
| D．reach the destination on time |
The taxi driver did not charge the old woman because he.
| A．wanted to do her a favor |
| B．shut off the meter by mistake |
| C．had received her payment in advance |
| D．was in a hurry to take other passengers |
What can we learn from the story?
| A．Giving is always a pleasure. |
| B．People should respect each other. |
| C．An act of kindness can bring people great joy. |
| D．People should learn to appreciate others’ concern. |
A new study warns that about thirty percent of the world's people may not have enough water by the year 2025.
A private American organization called Population Action International did the new study. It says more than three-hundred-thirty-five-million people lack enough water now. The people live in twenty-eight countries. Most of the countries are in Africa or the Middle East.
P-A-I researcher Robert Engelman says by the year 2025, about three-thousand-million people may lack water. At least 18 more countries are expected to have severe water problems. The demand for water keeps increasing. Yet the amount of water on Earth stays the same.
Mr. Engelman says the population in countries that lack water is growing faster than in other parts of the world. He says population growth in these countries will continue to increase.
The report says lack of water in the future may result in several problems. It may increase health problems. Lack of water often means drinking waters not safe. Mr. Engelman says there are problems all over the world because of diseases, such as cholera, which are carried in water. Lack of water may also result in more international conflict. Countries may have to compete for water in the future. Some countries now get sixty percent of their fresh water from other countries. This is true of Egypt, the Netherlands, Cambodia, Syria, Sudan, and Iraq. And the report says lack of water would affect the ability of developing to improve their economies. This is because new industries often need a large amount of water when they are beginning.
The Population Action International study gives several solutions to the water problem. One way, it says, is to find ways to use water for more than one purpose. Another way is to teach people to be careful not to waste water. A third way is to use less water of agriculture.
The report also says long-term solutions to the water problem must include controls on population growth. It says countries cannot provide clean water unless they slow population growth by limiting the number of children people have. are expected to have severe water problems by the year 2025.
| A．46 countries | B．18 countries |
| C．28 countries | D．No countries |
All the following are true except .
| A．Lack of water may cause conflict between countries |
| B．New industries need a lot of water |
| C．There are solutions to the water problem |
| D．Egypt now has enough fresh water |
.What can be inferred from the passage? .
| A．There is connection between providing clean water and slowing population growth |
| B．Lack of water may also result from international conflict |
| C．The ability of developing has nothing to do with lack of water |
| D．It is not known whether diseases have something to do with lack of water |
The best title of the passage would be .
| A．World Conflict | B．World Water Shortage |
| C．Diseases and Water | D．Population and Water |
Dolphins call out the specific names of loved ones when they become separated, a study finds．Other than humans, they are the only animals known to do this, according to the study．The big difference with dolphins is that these communications consist of whistles（鸣叫）, not words．
Earlier research found that dolphins have a “signature whistle” that would be somewhat like human shouting, “Hey everybody! I’m an adult healthy male named George, and I mean you no harm．”
The new finding is that dolphins also say the names of certain other dolphins．“Animals produced copies of the same sound when they were separated from a close partner．This supports our belief that dolphins copy another animal’s signature whistle when they want to reunite with that animal,” Stephanie King, who led the study, says．
King and her colleagues collected acoustic（声音的）data from wild dolphins around Sarasota Bay, Florida, from 1984 to 2009．The researchers also studied four adult male dolphins housed at the Seas Aquarium, also in Florida．
Those males are adults that keepers named Calvin, Khyber, Malabar and Ranier, all of whom, as well as all of the wild ones, developed their own signature whistles that served as names in communication with other dolphins．
“A dolphin uses its signature whistle to broadcast its identity and announce its presence．The signature whistles allow animals to identify one another over long distances and allow animals to recognize one another and to join up with each other,” King explains．“Dolphin whistles can be heard up to 20km away, depending on water depth and whistle frequency（频率）．”
The researchers said dolphins copy the signature whistles of loved ones, such as a mother, when the two are separated．These “names” are always used in positive situations, and are only directed toward loved ones．
While researchers are often unwilling to apply the word language to non-human communications, dolphins clearly have a very complex communication system．The underlined word “housed” in Paragraph 4 probably means “_________”．
| A．raised | B．saved | C．discovered | D．hunted |
Which one plays a part in whether dolphin whistles can be heard over a distance?
| A．The dolphin’s identity． |
| B．The water temperature |
| C．The whistle frequency． |
| D．The dolphin’s age． |
When do dolphins copy the signature whistles of loved ones?
| A．When there is a fight． |
| B．When their keeper comes． |
| C．When they are apart． |
| D．When they are hungry． |
The passage probably is taken from______
| A．A magazine about scientific advances． |
| B．A website about various animals． |
| C．A report on animal acoustics． |
| D．An essay about the relationship between humans and animals． |
Many songs, poems, and books have been written on love’s strong effect on people. The state of being in love has even been compared to being sick or mad. A study by Professor Semir Zeki of University College London has found that love does affect people’s brains by making them feel great.
Zeki studied young men and women who had recently fallen in love. He found that, when they were looking at photos of their loved ones, there was heightened activity in four areas of their brains. These areas deal with emotions, and one of them, in particular, is known to respond to drugs that cause feelings of great joy and excitement.
Interestingly, the study also found a lack of activity in two other areas of the brain when the volunteers looked at their lovers’ photographs. One of these areas is linked to feelings of sadness, while the other is often active in people suffering from depression. It seems love really can be uplifting.
The state of being in love, according to some scientists, may actually be good for your health. Although scientists know that being in love can make a person feel great, the exact influence of love on a person’s health is harder to determine. However, scientists say that people do need love in order to live healthy lives.
According to Dr. Thomas Lewis, people need to be in relationships because that is how we are designed. He says the brain can only maintain(保持) the overall stability of a person’s immune(免疫) system, bodily rhythms, and heart if it receives input(输入) from outside the body in the form of emotional connections with others.
Professor Antonio Damasio has a similar view. He says that love enriches a person’s imagination and creativity, and makes a person’s body work better. He also believes that love can even improve the body’s ability to fight against disease. Damasio’s wise words of advice are “ Choose love and you will live longer.”What is the main idea of this passage ? __________.
| A．love can really cause people active |
| B．love has an effect on songs and books |
| C．love is linked with emotion |
| D．love is what we need |
What does the underlined word “uplifting” mean? It means __________.
| A．inspiring | B．available | C．cold | D．mad |
From the passage we can conclude that__________.
| A．People write songs, poems and books to say love is the sweetest thing |
| B．nobody but Professor Semir Zeki has understood love does affect people’s brains |
| C．being in love sometimes may make someone act as if he/ she were mad |
| D．love causes heightened activity in all areas of a person’s brains |
Which of the following statements is not true?
| A．Some scientists have the idea that love does good to people. |
| B．It is possible for scientists to decide how much influence love can give people. |
| C．People are born to be in need of getting on touch with each other. |
| D．A person’s health depends on partly on emotional connections with others. |
My 18-month-old son, Adam, called from the front door．“Look, Mama! Doggie!” I dropped what I was doing and stuck my head out the door．Brandy, our next-door neighbor’s 11-year-old dog, was over again．“Go away!” I shouted．
Brandy’s owner had died about a month earlier．The woman’s family had emptied the house and stuck a “For Sale” sign in the front yard, but the family had left old Brandy behind．For weeks, she’d been wandering around the neighborhood．
It wasn’t that I disliked dogs or anything like that．I just didn’t think about them very much．I never had a dog growing up and had never thought to get one．
Brandy went away and I stayed outside with Adam．Then the phone rang．I went inside to take the call．When I came back, Adam was gone．I searched the yard, front and back, then the basketball court and public pool．No trace of him．I was so nervous that I ran home and called the police, then my husband．
Police searched the neighborhood．Suddenly I heard another sound: a dog barking．“It’s coming from the woods,” one of my neighbors said．We followed the barking to a wooded cliff（悬崖）．There we found my son, and he was just inches away from the edges of the cliff, fast asleep．Brandy was beside him, leaning（倚靠）against him to keep him away from the edge．When I picked Adam up, Brandy sank down on her side, breathing quickly．She must have been holding Adam there for hours!
I thanked the police and brought Adam and Brandy back to our house．She hesitated a moment on our doorstep, no doubt remembering the time I’d driven her away．
“Come on, girl,” I said．“This is your home now．” Brandy stepped in, and once she saw she was really welcome, she relaxed and lay down on the floor just inside the door．She’d done a great thing, and I wondered if she knew it ．She’d certainly touched me in a way that no animal ever had．What a pity a dog like Brandy had been left behind!What is the correct order for the events in the story about Brandy?
a．She was left behind by her owner’s family．
b．She stepped into the woman’s house．
c．She appeared at the woman’s front door．
d．She stayed beside the woman’s son for hours．
| A．d, a, b, c | B．a, c, b, d |
| C．c, d, b, a | D．a, c, d, b |
What did the woman do when she first saw Brandy?
| A．She gave her some food． |
| B．She drove her away． |
| C．She took her home． |
| D．She said thank you to her． |
How were they able to be aware that the woman’s son was near the cliff?
| A．By searching the neighborhood． |
| B．By hearing a dog barking． |
| C．By following a dog’s footsteps． |
| D．By hearing her son’s crying． |