If blood is red, why are veins (靜脈) blue? Actually, veins are not blue at all. They are more of a clear, yellowish color. Although blood looks red when it’s outside the body, when it’s sitting in a vein near the surface of the skin, it’s more of a dark reddish purple color. At the right depth, these blood-filled veins reflect less red light than the surrounding skin, making them look blue by comparison. Which works harder, your heart or your brain? That kind of depends on whether you’re busy thinking or busy exercising. Your heart works up to three times harder during exercise, and shifts enough blood over a lifetime to fill a supertanker(超級油輪). But, in the long run, your brain probably tips it, because even when you’re sitting still your brain is using twice as much energy as your heart, and it takes four to five times as much blood to feed it. Why do teeth fall out, and why don’t they grow back in grown-ups? Baby (or “milk”) teeth do not last long; they fall out to make bigger room for bigger, stronger adult teeth later on. Adult teeth fall out when they become damaged, decayed(腐爛)and infected by bacteria. Once this second set of teeth has grown in, you’re done. When they’re gone, they are gone. This is because nature figures you’re set for life, and what controls regrowth of your teeth switches off. Do old people shrink(收縮)as they age? Yes and no. Many people do get shorter as they age. But, when they do, it isn’t because they’re shrinking all over. They simply lose height as their spine (脊柱) becomes shorter and more curved due to disuse and the effect of gravity (重力). Many (but not all) men and women do lose height as they get older. Men lose an average of 3-4 cm in height as they age, while women may lose 5 cm or more. If you live to be 200 years old, would you keep shrinking till you were, like 60 cm tall, like a little boy again? No, because old people don’t really shrink! It is not that they are growing backwards—their legs, arms and backbones getting shorter. When they do get shorter, it’s because the spine has shortened a little. Or, more often, become more bent and curved. Why does spinning make you dizzy)? Because your brain gets confused between what you’re seeing and what you’re feeling. The brain senses that you’re spinning using special gravity-and-motion-sensing organs in your inner ear, which work together with your eyes to keep your vision balance stable. But when you suddenly stop spinning the system goes out of control, and your brain thinks you’re moving while you’re not. Where do feelings and emotions come from? Mostly from an ancient part of the brain called the limbic system(邊緣系統(tǒng)). All mammals have this brain area — from mice to dogs, cats, and humans. So all mammals feel basic emotions like fear, pain and pleasure. But since human feelings also involve other, newer bits of the brain, we feel more complex emotions than any other animal on this planet. If exercise wears you out, how can it be good for you? Because our bodies adapt to everything we do to them. And as far as your body is concerned, it’s “use it, or lose it”! It’s not that exercise makes you healthy, it’s more that a lack of exercise leaves your body weak and easily affected by disease. |
A.Blue | B.Light yellow |
C.Red | D.Dark reddish purple |
A.Because their spine is in active use. |
B.Because they are more easily affected by gravity. |
C.Because they keep growing backwards. |
D.Because their spine becomes more bent. |
A.In the long run, our brain probably works harder than our heart. |
B.When our brain senses the spinning, we will feel dizzy. |
C.The brains of the other mammals are as complex as those of humans. |
D.Our feelings and emotions come from the most developed area in our brain. |
A.To give advice on how to stay healthy. |
B.To provide information about our body. |
C.To challenge new findings in medical research. |
D.To report the latest discoveries in medical science. |
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A.they can eat its parasites |
B.they consider the sheep as their shelter |
C.they enjoy traveling with the sheep |
D.they find the position most comfortable |
A.birds and parasites | B.sheep, birds and parasites |
C.parasites and sheep | D.birds and sheep |
A.comfort | B.light | C.oxygen | D.food |
A.Some plants depend on each other for food. |
B.Some animals and plants develop their relationship easily. |
C.Some animals and plants depend on each other for existence. |
D.Some animals live better together. |
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A.people did not know how to put out the fire |
B.Elias Howe thought Thimonnier had stolen his invention |
C.the sewing machines couldn’t work finally |
D.workers who feared the loss of their jobs to a machine set fire |
A.Because the judge was against Singer for his unfriendly attitude. |
B.Because Howe had already patented the lockstitch used by Singer. |
C.Because Singer had borrowed money from Howe and never repaid it. |
D.Because Singer and Howe had both invented the same machine. |
A.A Stitch in Time Saves Nine |
B.The Case between Howe and Singer |
C.Patent Laws on the Sewing Machine |
D.The Early History of the Sewing Machine |
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A.One who plays with great passion. |
B.One who plays unique music. |
C.One who plays creatively. |
D.One who has a sense of vision. |
A.watch classical music competitions |
B.a(chǎn)ssign the silent videos |
C.pick out the best three competitors |
D.decide who the winner is |
A.Her love for music. |
B.Her desire to explore. |
C.Her experience as a competitor. |
D.Her curiosity in musical education. |
A.A text book. | B.A sports magazine. |
C.A story book. | D.A science website. |
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科目:高中英語 來源:不詳 題型:完形填空
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A.with physical and emotional problems |
B.short of time and money |
C.unable to give birth to children |
D.separated from each other for a long time |
A.the treatment of mental diseases |
B.the reserve of heart diseases |
C.the cure of gene-related diseases |
D.the bearing of babies |
A.it has brought about benefits so far |
B.it may be out of human control |
C.people still know little about it |
D.people are afraid of such technology |
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A.Because hungry people needed time to fill their stomach. |
B.Because Radel wanted to create two groups of testers, hungry and non-hungry. |
C.Because noon was not the right time for any experiment. |
D.Because Radel needed time to select participants in terms of body mass index. |
A.Human’s senses aren’t just delivering a strict view of what’s going on in the world. |
B.What’s perceived by our senses affects our way of thinking. |
C.Human brains can really be at the disposal of our motives and needs. |
D.Thinking processes guarantee the normal functions of our senses. |
A.42 participants are too small a number for a serious investigation. |
B.An experiment with hungry and non-hungry participants is not reliable. |
C.Our thinking processes are independent of our senses. |
D.Humans can perceive what they need without involving high-level thinking processes |
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A.Going Green. | B.Protecting the Planet. |
C.Keeping Open-Minded | D.Celebrating Our Green Year. |
A.they were expected to follow the green fad |
B.they didn’t know how to educate other people |
C.they were unwilling to reduce their energy |
D.they needed to perform unusual green tasks |
A.They tried to get out of their ungreen habits. |
B.They ignore others’ ungreen behavior. |
C.They chose better chemical cleaners. |
D.They sold their home-made food. |
A.The government will give support to the green people. |
B.The couple may continue their project in the future. |
C.Some people disagree with the couple’s green ideas. |
D.Our Green Year is becoming a national campaign. |
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A.Using river water. | B.Throwing batteries away. |
C.Paving parking lots. | D.Throwing rubbish into lakes. |
A.All water shortages are due to human behavior. |
B.It takes a lot of effort to meet our water needs. |
C.There is much we can do to reduce family size. |
D.The average family in America makes proper use of water. |
A.show us how to fix leaks at home |
B.tell us how to run a dishwasher |
C.prove what drinking glass is best for us |
D.suggest what we do to save water at home |
A.Why paving roads reduces our water |
B.how much we depend on water to live |
C.why droughts occur more in dry climates |
D.how human activity affects our water supply |
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