Do you drink water that's been left sitting out overnight or even for another day? Have you noticed it tastes different?
Tap water that has been left to sit out slowly begins to acquire an off taste. Many people think that this is because of microorganisms(微生物). But that's not what makes old water taste not fresh. For that we can thank carbon dioxide. After about 12 hours, tap water starts to go flat as carbon dioxide in the air starts to mix with the water in the glass, lowering its pH and giving it an off taste. But it's most likely safe to drink.
However, back to those microorganisms. If you use a dirty glass day after day, there is more of a chance of bacteria making themselves known; a risk that increases if you share the glass with another mouth as well. But assuming you use a fresh glass every few days, you probably won't have a problem unless the glass has been touched by dirty fingers, and especially if those dirty fingers went unwashed after using the bathroom.
As for plastic water bottles that have been left out in the sun or in the car, step away from the bottle, warns Dr. Kellogg Schwab, director of the Johns Hopkins University Water Institute. "A chemical called bisphenol-A, or BPA, along with other things used to make plastic can leach(过滤) into your water if the bottle heats up or sits in the sun," he explains. BPA, as you probably know, has been linked to everything from heart disease to cancer.Schwab also adds that plastic used for commercial bottled water isn't meant to be washed or refilled, so use only one time and recycle. Or don't buy them at all; use refillable water bottles instead.
Tap water begin to acquire an off taste because of .
| A．BPA | B．the glass |
| C．the microorganism | D．carbon dioxide |
According to Paragragh 2 , tap water that's been left sitting out for 12 hours____.
| A．tastes better | B．is still safe to drink |
| C．contains few microorganisms | D．is most likely undrinkable |
What should we do with plastic water bottles that have been left out in the sun or in the car?
| A．Throw them away. | B．Refill them with fresh water. |
| C．Use them after they cool down. | D．Clean them and use them again. |
Which of the following is true about BPA?
| A．It is safe for people to use. |
| B．It is a kind of new material. |
| C．It can cause great harm to people. |
| D．It is the main material to make plastic. |
Light travels at a speed which is about a million times faster than the speed of sound. In one second, light travels about 300,000km, but sound travels only 344m. You can get some idea of this difference by watching the start of a race. If you stand some distance away from the starter, you can see smoke come from his gun before the sound reaches your ears. This great speed of light produces some strange facts. Sunlight takes about 8 minutes to reach us. If you look at the light of the moon tonight, remember that the light rays（光线）left the moon 1.3 seconds before they reached you. The nearest star is so far away that the light which you can see from it tonight started to travel towards you four years ago at a speed of nearly 2 million km per minute. In some cases the light from one of tonight’s stars started on its journey to you before you were born.
Thus, if we want to be honest, we cannot say “ The stars are shining tonight.” We have to say, “ The stars look pretty. They were shining four years ago but their light has only just reached Earth.” Light speed is ________ than sound speed.
| A．millions times faster | B．a million times slower |
| C．about millions of times faster | D．about a million times faster |
If you stand 200 meters away from a man who is firing a gun to start a race, you will find out that _____.
| A．you can hear the gun before you see the smoke. |
| B．sound does not travel as fast as light. |
| C．the sound of the gun will reach you before the man fires his gun. |
| D．sound travels about a million times faster than light. |
What does “ it” refer to?
| A．moon light | B．light rays | C．the nearest star | D．the moon |
The scientific way of saying “ The stars are shining tonight” should be________.
| A．the stars have been shining all the time. |
| B．the stars seen tonight will be shining four years later. |
| C．the stars were shining long ago but are seen tonight. |
| D．the starlight seen today could be seen four years ago. |
Do you still get free plastic bags from the supermarkets? Things have changed.
China has banned free plastic bags at shops and supermarkets, and people have to pay for using plastic bags. The rule started on June 1, 2008. It came because our country tried to make litter less. Making super-thin plastic bags has also been banned.
The Chinese once used about 3,000,000,000 plastic shopping bags a day, and they have caused pollution of the environment. The bags have become a main cause of plastic pollution because they are easy to break and people throw them away here and there. So the Chinese people are encouraged to bring their own bags for shopping.
What kind of shopping bag is the best to bring? Some students in Anhui have a good idea. They make their own shopping bags. They use old clothes to make cloth bags, and send them to their parents as presents. They also ask their parents and friends to use cloth bags instead of plastic ones. They think it is their duty to protect the environment. People in China have to _____ now.
| A．throw plastic bags here and there |
| B．collect plastic bags in the street |
| C．pay for using plastic bags at shops and supermarkets |
| D．use free plastic bags at shops and supermarkets |
China made this rule because plastic bags were bad for the ______.
| A．environment | B．litter |
| C．shops | D．supermarkets |
Some students in Anhui ______.
| A．ask their parents to make cloth bags | B．make cloth bags themselves |
| C．pick up plastic bags everywhere | D．buy cloth bags for their parents |
What’s the main idea of this article?
| A．Making super-thin plastic bags has been banned in China. |
| B．The bags have become a main cause of plastic pollution. |
| C．Some students in Anhui begin to make their own shopping bags. |
| D．To protect the environment, free plastic bags have been banned in China. |
One day, I happened to talk to a stranger (陌生人) on the bus. When he found out that I was from Chicago, he told me that one of his good friends lived there and he wondered if I happened to know him. At first I wanted to say that it was foolish (愚蠢的) to think like that, for from all the millions of people in Chicago, I could not possibly know his friend. But, instead, I just smiled and said that Chicago was a very big city. He was quiet for a few minutes, and then he began to tell me all about his friend.
He told me that his friend was an excellent tennis player and that he even had his own tennis court (网球场). He added that he knew a lot of people with swimming pools, but that he only knew two people in the country who had their own tennis courts. And his friend in Chicago was one of them. I told him that I knew several people like that, for example, my brother and my next-door neighbor. I told him that my brother was a doctor and he lived in California. Then he asked where my brother lived in California. When I said Sacramento, he said that last year his friend spent the summer in Sacramento and lived next door to a doctor. The doctor had a tennis court. I said that my next-door went to Sacramento last summer and lived in the house next to my brother’s. For a moment, we looked at each other, but we did not say anything.
“Would your friend’s name happen to be Roland Kirkwood?” I asked finally. He laughed and said, “Would your brother’s name happen to be Dr. Ray Hunter?” It was my turn to laugh. Which of the following is true?
| A．The story happened in Chicago. |
| B．The writer’s brother lived in Sacramento. |
| C．Both the writer and the stranger lived in Chicago. |
| D．Both the writer and his brother lived in California. |
The writer said that Chicago was a very big city. That means _____________.
| A．it was possible for him to happen to know the stranger’s friend |
| B．he didn’t want to look for the stranger’s friend |
| C．he didn’t know the stranger’s friend |
| D．it was impossible to find the stranger’s friend |
How many persons does the story involve (涉及)?
| A．Four. | B．Five. | C．Six. | D．Seven. |
Which is the best title of the story?
| A．On a bus | B．Two tennis players |
| C．One in a million | D．Chicago is a large city |
I don’t often lose things and I’m always careful with money, so I was quite surprised when I reached for my wallet and it wasn’t there. At first, I thought it was possible that I could have left it at home. Then I remembered taking it out to pay the taxi, so I knew I had it with me just before I walked into the restaurant. I wondered if it was possible that it could have dropped out of my pocket while I was eating dinner. I turned and walked back to the table where I had been sitting. Unluckily, there were several people sitting at the table at that time, so I had the waiter go over to the table to see if my wallet was on the floor. While the waiter was looking for it, the head of the restaurant came up to me and asked me if anything was wrong. I told him what had happened. He asked me to report the missing wallet to the police. I told him I didn’t want to do so; I was in a hurry because I had to reach my waiting room before two o’clock, where some people were waiting to see me. I also told him that my biggest worry at the moment was how I was going to pay for the meal. He told me not to worry about that. He asked me to write down my name and address, and he said he would send me a bill (帐单). When the writer couldn’t find his wallet, his first thought was that________
| A．it had been given to the taxi-driver |
| B．he had dropped it in the taxi |
| C．he had lost his wallet again |
| D．it might be left at home |
The writer thought he must have the wallet with him because___________.
| A．he had paid the taxi-driver |
| B．he had paid the bill of the meal |
| C．the waiter had seen it on the table |
| D．the waiter was looking for it on the floor |
Why do you think the writer turned and walked back to the table?
| A．He would phone the police about the missing of his wallet. |
| B．He wondered if he had dropped his wallet while eating. |
| C．The head of the restaurant wanted to know what was wrong. |
| D．Several people were sitting at the table at that time. |
The writer of the story is probably a _________.
| A．doctor | B．cook | C．school teacher | D．newspaper reporter |
When Tom finished his studies at the university (大学), he began to look around for a job. He did not know what he would like to do, but one of his uncles had worked for the government for thirty years, and he advised Tom to try to get a job of the same kind, so he went for an exam one day. He was successful, and his first job was in a large government office in London.
When Tom had been working there for a few weeks, his uncle came to visit the family one Saturday evening. He was pleased that his nephew (侄子) had got a job working for the government, and he asked him a lot of questions about it.
One of the questions he asked was, “How many people work in your department (部门), Tom?”
The young man thought for a few moments and then answered, “About half of them, Uncle Jim.”When he graduated (毕业) from university, Tom was not ________.
| A．interested in getting any information from the government |
| B．looking for a good-paying job with excellent hours |
| C．good at making decisions |
| D．very good at science |
What did Tom think of his uncle’s advice?
| A．He did not like it. | B．He thought it was good |
| C．He refused to take it. | D．He was unable to follow it. |
The uncle wanted to find out ________.
| A．what his nephew was doing |
| B．how his nephew was getting on with his job |
| C．whether his nephew could understand him or not |
| D．what his nephew had expected |
In fact Tom’s answer means that __________.
| A．the people working in the government office were in many groups and they worked in turn |
| B．most of the government workers were not working hard |
| C．only half of the government workers went to work on time |
| D．the government office had more people than needed |
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