【推荐2】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(获得) an off taste. Many people think that this is because of microorganisms. 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(假设) 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.

1. Tap water begin to acquire an off taste because of______ .

A．BPA	B．carbon dioxide
C．the glass	D．the microorganism

2. According to Paragragh 2 , tap water that's been left sitting out for 12 hours____.

A．is still safe to drink	B．tastes better
C．contains few microorganisms	D．is most likely undrinkable

3. 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．Clean them and use them again.

C．Use them after they cool down.

D．Refill them with fresh water.

4. 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.

【推荐3】An unusual experiment in Botswana suggests that painting eyes on the rear ends (臀部) of cows may help protect them from large predators (食肉动物)like lions. Protecting cows could also end up protecting the lions from angry farmers.

Large predators like lions are under pressure. Much of the land they used to roam (漫步) has been taken over by humans. Many are hunted illegally. One serious threat to large predators comes from farmers, who often shoot or poison them after losing farm animals for their attacks.

This has long been a problem in the Okavango Delta. Some parts of the Okavango are protected, but there are also many small farms in the area, with between 6 and 100 cows. Lions are the biggest threat to cattle in the area. At night, farmers normally keep their animals in closed areas protected from predators. But in the daytime, when many predators are most active, the cattle are allowed out to eat grass.

Scientists from the University of New South Wales wondered if painting pictures of eyes on the cows’ rear ends might protect them. The idea isn’t as strange as it may sound. There are many examples of animals such as butterflies or fish using fake (假的) “eyes”to protect themselves.

Working with over 2, 000 cows on 14 different farms in the Okavango area, the scientists tested their ideas in a four-year study. The researchers separated the cows into three different groups. They painted large eyes on the rear ends of one group of cows. The second group got simple Xs. The final group got nothing.

The eyes worked very well. Of the 683 cows with eyes painted on them, none were killed in the four-year period. Cows with nothing on their rear ends didn't do so well. Fifteen of the 835 cows with bare backsides were killed. The scientists were surprised to learn that even Xs seemed to give the cows some protection. Only 4 of the 543 cows with Xs were killed.

1. Why do famers become a big threat to large predators?

A．They poison them to defend themselves.

B．They hunt them for their meat and fur.

C．They shoot them just for pleasure.

D．They kill them to protect farm animals.

2. What is the purpose of mentioning butterflies in the text?

A．They have beautiful eyes.	B．Their fake “eyes” work.
C．They get close to nature.	D．Their fake “eyes” vary.

3. In what way is the fifth paragraph developed?

A．By sharing the reasons for tests.	B．By listing the number of cows.
C．By presenting the facts of tests.	D．By comparing the results of tests.

4. What does the text mainly talk about?

A．Lions are in danger of being hunted illegally.	B．Farmers become enemies of lions.
C．Protecting cows proves to be ineffective.	D．Fake eyes protect cows from lions.

【推荐1】When we found him, he was a sorry sight. His clothes were torn, his hands bleeding. Before we reached him, we saw him fall. He lay a moment. Then he pulled himself to his feet, walked unsteadily a few yards through the woods and fell again. After we got him out, we went back to find the gun that he had thrown down. His tracks showed that for two days he had circled in the forest, within 200 yards of the road. His senses were so dulled by fear and tiredness that he did not hear the cars going by or see the lights at night. We found him just in time.

This man, like others before him, had simply been frightened when he knew he was lost. What had been a near disaster might have turned out as only a pleasant walk, if he had made a few preparations before he stepped from the highway or off a known path.

Whatever sense of direction that a man may have, it’s still largely a question of observation. A skilled woodsman always keeps an eye on his surroundings. He notes the shape of a mountain, the direction water flows through a swamp (沼泽), and the way a tree leans across a path. With these in mind, he is still likely to turn around many times, but he is seldom lost.

There are exceptions, of course, and once in a while a man does come across some strange problem that puts him into the “lost” situation. A rainstorm may catch him without a compass in his pocket. Darkness may find him in a rough area, where travel is dangerous without a light.

When this happens, the normal first reaction is the fear of being laughed at as a result of his poor knowledge in the woods. He may also be concerned about the inconvenience that he will cause his friends when he doesn’t show up. This false pride may lead him to keep on the move in a false effort to find his way against all difficulties.

The person who thinks ahead is seldom in great danger. He’ll be safe if he observes carefully, thinks ahead, and remains calm.

1. The writer suggested that if the man had not been found, ________ .

A．he would have been shot by a gun	B．he would have become confused
C．he would have been attacked by wild animals	D．he would have been in great danger

2. What is the most important when a person tries to find his way in the woods?

A．Intelligence.	B．Observation.
C．Direction.	D．Chance.

3. According to the text, if a person gets lost in the forest, at the very beginning, ________.

A．he will worry about being laughed at

B．he will push himself to find his way out

C．he will feel sorry that he didn’t prepare well enough

D．he will feel it is convenient to ask for help from his friends

4. The writer tells the story of the lost man as an example of people who ________.

A．go into the woods by themselves

B．keep their head when they are in trouble

C．are frightened when they think they are lost

D．don’t know how to signal for help properly