A

    Many people think the camel stores water in its hump (驼峰), but it does not. Instead, the camel stores something else there—food. The camel's hump is really a hump of fat (脂肪). The camel is often called "a ship of the desert". When the camel is not travelling and is in a place where there is much food and water, it eats and drinks a lot. As it does so, its hump rises from the fat its body makes. Then, when the camel is travelling through the desert and when there is no food, it can live off the stored fat.

    A camel can go on for days or weeks with little food or water. However, when its hunger reaches the starvation (饿死)point, its hump shrinks (收缩) and may even slip off its back and hang down its side.

    Camels are not fussy (挑剔的) about what they eat. Thorny (多刺的) plants don't hurt their mouths, grass of any kind will do and so will hay, dry grain and cactuses (干草, 干粮, 仙人掌).

There are one­ hump camels and two­ hump camels. Camels with one hump are called Arabian camels. They come from North Africa. Camels with two humps are from Asia.

    Do equations and historical( 历史的) facts give you a headache? A change in the school timetable(课程表) may be the cure.

    This  suggestion  is  based  on  a  recent  study  carried  out  by  scientists  from  Royal  Holloway, University of London, the UK. They found that teenagers could get higher marks in math if they studied in the mornings and better grades in history if they were taught in the afternoons.

    The researchers studied students' grade reports, class timetables and absence rates( 缺席率) at a middle school in Bulgaria over nine years. The results showed that when teenagers had math classes earlier in the day, they scored about 7 percent higher in tests than when taught in the afternoon. Lower-ability students feel stressed most when they were studying math in the afternoon. In history, students taught in the afternoon scored about 6 percent higher than when they were taught in the morning. However, there was no sign that similar patterns( 模 式 ) work for other subjects such as languages or geography.

    Velichka Dimitrova, who did the study, said the findings show that we perform( 表 现 ) better at different times of the day. “In the morning, our brains are better and fresher, so we are better at doing something like problem solving, where we require more speed and attention” Dimitrova told The Telegraph. “In the afternoon, it seems that this process slows down. On the other hand, history is more suitable for the afternoon, when we are more creative and open to discussion,” she said. Subjects such as foreign languages require both memory and creativity. This is perhaps why the time of day had no influence on language learning.

    Time-of-day influences such as these are believed to have something to do with the body clock.

    This is the system in our bodies that controls when we need to sleep. Some schools in the US and UK have tried later school starting times for teenagers, whose body clocks change as they grow into adults. Dimitrova believes schools should jump at this chance to improve their students' performance just by changing their timetables.

    Bamboo(竹子) is one of nature s most surprising plants. Many people call this plant a tree, but it is a kind of grass.

    Like other kinds of grass, a bamboo plant may be cut very low to the ground, but it will grow back very quickly. A Japanese scientist reported one bamboo plant which grew 1.5 metres in 24 hours! There are more than 1, 000 kinds of bamboo. Bamboo grows almost everywhere in the world, but in Europe, they can't grow.

    Not all bamboo looks the same. Some bamboo plants are very thin. They may only grow to be a few centimetres wide while others may grow to be more than 30 centimetres across. This plant also comes in different colours, from yellow to black to green.

    Bamboo has been used to make many things such as hats and kitchen tools. Because it is strong, bamboo is also used to build buildings.

    Many Asian countries have used bamboo for hundreds of years. They often use bamboo for buildings and supporting(支撑) new buildings and bridges while they are being built.

    In Africa, poor farmers are taught how to bring water using bamboo. These African countries need cheap ways to bring water because they have no money, and their crops often die from no rain and no water. Bamboo pipes(管子) help poor farmers bring water to their thirsty fields without spending much money.

    Man has a big brain(脑). He can think, learn and speak. Scientists always say that men are different from animals because they can think and learn. They know now that dogs, rats, birds can learn too. They are beginning to understand that men are different from animals because they can speak. Animals cannot speak. They make noises when they are afraid, or angry or unhappy. Apes(类人猿) can understand some things more quickly than humans. One or two of them can learn a few words. But they cannot join words to make sentences. They cannot think like us because they have no language(语言). They can never think about the future. Language is a wonderful thing. Man can build a modern world because he has language. Every child can speak his own language very well when he is four or five, but no animals learn to speak. How do children learn it? Scientists do not really know. What happens inside our body when we speak? They do not know. They only know that man can speak because he has a brain.