Have you ever wondered why birds sing? Maybe you thought that they were just happy. After all, you probably sing or whistle(吹口哨) when you are happy.

    Some scientists believe that birds do sing some of time just because they are happy. However, they sing most of the time for a very different reason. Their singing is actually a warning to other birds to stay out of their territory.

    Do you know what a “territory” is? A territory is an area that an animal, usually the male, claims as its own. Only he and his family are welcome there. No other families of the same species(物种) are welcome. Your yard and house are your territory where only your family and friends are welcome. If a stranger should enter your territory and threaten you, you might shout. Probably this would be enough to frighten him away.

    If so, you have actually frightened the stranger away without having to fight him. A bird does the same thing. But he expects an outsider almost any time, especially at nesting(筑巢) season. So he is screaming all the time, whether he can see an outsider or not. This screaming is what we call a bird's song, and it is usually enough to keep an outsider away.

    Birds sing loudest in the spring when they are trying to attract a mate（配偶）and warn others not to enter the territory of theirs.

    You can see that birds have a language all their own. Most of it has something to do with attracting mates and setting up territories.

    The British are known for their sense of humor. However, it is often difficult for foreigners to understand their jokes. The main point to remember is that the British often use understatement.

    Understatement means saying less than you think or feel. For example, if someone gets very wet in a shower of rain, he might say, “Its a little damp (潮湿的) outside.” Or, if someone is very impolite and shouts at another person, someone else might say, “She isn't exactly friendly.” Understatement is often used in unpleasant situation or to make another person look silly. Understatement plays an important part in British humor.

    Another key to understanding British humor is that the British like to make fun of themselves as well as others. They often laugh about the silly and unpleasant things that happen to our everyday life when someone accidently falls over in the street. They also like to make jokes about people from different classes of society. They like to make jokes about their accents, the way they dress and the way they behave. What's more, the British love to watch comedies (喜剧) about people who do not know how to behave in society. The comedies series Mr. Bean is a good example of this kind of humor.

    Mr. Bean is the character created by British actor Rowan Atkinson in 1990. Mr. Bean doesn't talk often, and instead he uses his body movement and facial expressions to make people laugh. Perhaps what makes Mr. Bean so funny is that he does things that adults in the real world cannot do. Mr. Bean is popular in many countries around the world because you do not have to speak English to understand the humor. Because of this, many people have become familiar with the British sense of humor.

阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。

    Actually, long-distance bicycle camping is one of the most pleasurable activities I have ever experienced.

    I generally sleep poorly at night, but in the woods on a tour, I sleep like a baby, falling asleep with the music of insects. In the morning, I am awakened by the cheeps of birds. I eat a snack before getting up, and then I quickly pack my sleeping bag, air mattress (垫), tent, and other things and get on with my road. I'm slower in the morning, having less speed but a greater desire to stop at pleasant spots and enjoy the beautiful scenery. Traveling by bike allows me to stop anywhere, such as grasslands, lakes, woods, and scenic spots. Near lunch, I find a small grocery and buy some bread, sandwiches and fruit. Then I will find a town park or other shady spots to wait out the high mid-day sun. In the afternoon, my speeds are higher, and I spend less time on stops. In the late afternoon, I start riding more slowly, and I start thinking about where I will stop. I finally find a place in the early evening, cook a simple meal and have a rest. As it starts to get dark, I put up my tent, crawl in and fall asleep.

    There are exciting times and difficult times as well. Visiting strange or famous places and accomplishing goals are always exciting to me. I meet and talk with interesting people along the way, sometimes other traveling cyclists. Appreciating beautiful views, meeting wild animals, and traveling up and down hills also. On the other hand, I may run into a rainy or hot spell(一段时间), have to repair my bike, or just find myself in a bad mood. The problems are infrequent and are easy to deal with. The pleasures remain in my mind for years.

    The quick action of Nick helped five people escape a fire on Hope Road. Nick said he usually left his house about 5:30 a.m. to do morning exercises, but that day he decided to stay at home to get his daughter ready for school. As he looked at his neighbor's house, he realized that it was on fire. "I saw smoke and flames and ran over and started beating on the side of the house shouting, 'Your house is on fire! Your house is on fire!'" Nick remembered it was at about 9 a.m. that the firefighters put out the fire.

    Beverly Penny and her husband, Clark, along with their younger daughters, were sleeping in the living room, next to the kitchen, when they heard Nick beating on the walls. She opened the bedroom door and black smoke came in. She managed to get her kids out. Her dog tried to hide under the bed, but Penny caught it by the leg and threw it out of the door. However, chickens in one of the rooms weren't so lucky.

    Firefighters got the call at about 7:05 a.m. "When we arrived with our fire trucks, there were heavy flames outside on the house," Jerry said. He called Nick a hero, saying that without his quick responses(回应) the result could have been much worse. "The firefighters were fast," Nick said. "They arrived here within about three minutes."

    "They did a great job, and I can't thank them enough," Penny said, then looked at what remained in the house and shook her head as tears rolled down in her eyes. "Everything I have is gone. Luckily nobody was hurt in the fire." She said the fire could have been caused by an electrical problem. "We've been having problems with mice, so that we could have had something to do with it," she added.

    We can make mistakes at any age. Some mistakes we make are about money. But most mistakes are about people. "Did Jerry really care when I broke up with Helen?" "When I got that great job, did Jim, as a friend, really feel good about it?" "And was Paul friendly just because I had a car?" When we look back, doubts like these can make us feel bad. But when we look back, it's too late.

    Why do we go wrong about our friends or our enemies? Sometimes what people say hides their real meaning. And if we don't really listen we miss the feeling behind the words. Suppose someone tells you, "You're a lucky dog." That's being friendly. But "lucky dog"? There's a bit of envy in those words. Maybe he doesn't see it himself. But bringing in the "dog" bit puts you down a little. What he may be saying is that he doesn't think you deserve your luck.

    "Just think of all the things you have to be thankful for" is another noise that says one thing and means another. It could mean that the speaker is trying to get you to see your problem as part of your life as a whole. But is he? Wrapped up in this phrase is the thought that your problem isn't important. It's telling you to think of all the starving people in the world when you haven't got a date for Saturday night.

    How can you tell the real meaning behind someone's words? One way is to take a good look at the person talking. Do his words fit the way he looks? Does what he says agree with the tone of voice? His posture(姿态)? The look in his eyes? Stop and think. The minute you spend thinking about the real meaning of what people say to you may save another mistake.

The college entrance examination is just around the corner. Homework and tests will keep many of you up late at night, and you may plan to make up for your lost sleep during the weekends. {#blank#}1{#/blank#} is it useful? A study published in the journal Current Biology completely has changed {#blank#}2{#/blank#} people used to think. It shows that the habit of sleeping in on weekends doesn't fix the damage done by a lack of sleep during the week. Even {#blank#}3{#/blank#} (bad), it may damage your health.