Can you remember a morning when you've woken up to the ring of your alarm clock and wished you could stay in bed? You haven't slept well, your hair is a mess. Worse, you can't stop yawning. Yawning is universal to humans and many animals. Cats, dogs and fish yawn just like humans do! Yawning is an involuntary(,) action during which you open your mouth and breathe deeply. The average duration of a yawn is about 6 seconds. The purpose and cause of yawning are still a mystery. Scientists are not sure what causes a yawn. People yawn when they are tired or bored, but they also yawn when they aren't. There are many ideas explaining why we yawn. One idea is that yawning is a way for the body to become more alert by taking in more oxygen. A yawn increases the heart rate, forces carbon dioxide out of the lungs and blood stream, and brings oxygen to the brain. But one study showed that volunteers given a lot of oxygen did not yawn any less than before, while those given a lot of carbon dioxide did not yawn more. Another idea is that early humans used yawning as a form of communication. If one decided it was time to sleep, they would tell the others by yawning and they would do it in return to show they agreed. A third explanation comes from psychology professor Gordon Gallup of University at Albany in New York. He said that as people yawn, they cool off their brains. "Brains are like computers." he said. "They only operate efficiently and effectively when they're cool. Many things connected to yawning, like being tired, make the brain hot, and yawning can reduce the heat." Scientists have sent people into space, and created terrible nuclear weapons, but there are lots of seemingly simple things, such as why we yawn, or hiccup , that they can't figure out. Next time you are in class in the morning, let out a big yawn and watch to see how many of your classmates yawn in response! What's the purpose of the description of how bad you may feel when you're woken up in the morning? A) To explain why humans yawn. B) To explain how humans start yawning. C) To lead into the topic of yawning. D) To complain about being woken up by the clock.
C
We have only one earth.In a world with limited land, water and other natural resources, the harm from the traditional business model is on the rise.Actually, the past decades has seen more and more forests disappearing and globe becoming increasingly warm.People now realize that this unhealthy situation must be changed, and that we must be able to develop in sustainable ways.That means growth with low carbon or development of sustainable products.In other words, we should keep the earth healthy while using its supply of natural resources. Today, sustainable development is a proper trend in many countries.According to a recent study, the global market for low-carbon energy will become three times bigger over the next decades.China, for example, has set its mind on leading that market, hoping to seize chances in the new round of the global energy revolution.It is how trying hard to make full use of wind and solar energy, and is spending a huge amount of money making electric cars and high-speed trains.In addition, we are also seeing great growth in the global markets for sustainable products such as palm oil , which is produced without cutting down valuable rainforest.In recent years the markets for sustainable products have grown by more than 50%. Governments can fully develop the potential of these new markets.First, they can set high targets for reducing carbon emissions and targets for saving and reusing energy.Besides, stronger arrangement of public resources like forests can also help to speed up the development.Finally, governments can avoid the huge expenses that are taking us in the wrong direction, and redirecting some of those expenses can accelerate the change from traditional model to a sustainable one. The major challenge of this century is to find ways to meet the needs of growing population within the limits of this single planet.That is no small task, but it offers new chances for sustainable product industries. What is the main purpose of the passage? A) To introduce a new business model. B) To compare two business models. C) To predict a change of the global market. D) To advocate sustainable development.
D
(Question)
The earth is not the only body that travels around the sun. With it are eight other planets, fellow members of the sun's family. Two of them, Mercury and Venus, are nearer while the other six, namely Mars, Jupiter, Saturn, Uranus, Neptune and Pluto, also in their given order from the sun, are farther from the sun than the earth is. The farther they are, the longer trips they make around the sun. People noticed long ago that these traveling bodies moved around in the sky in definite paths. It is a force called gravity that holds them in their paths. We know that every little bit of matter in the universe pulls upon every other bit of matter. The pull between two bodies is proportional to the product of their masses. Because the sun is so large the pull between the sun and the planets are thus great. If it were not for this pull, the planets would fly off into space. In the same way there exists a pull between the earth and the moon, which keeps the moon traveling in its orbit around our planet, the earth. Gravity holds you to its surface, and pulls back to it the ball which you throw into the air. Of course the ball also pulls on the larger earth but the earth is so much larger that the pull is not noticed. Now remember that large bodies exert a greater pull than smaller ones which contain less material. But each object in the universe, no matter how small, pulls on all other objects to some degree. Which two planets make the longest trips around the sun among all the planets in the solar system? A) Mercury and Venus. B) Neptune and Pluto. C) Saturn and Uranus. D) Mars and Jupiter.
(Answer)
B