Most groups of plants and animals are richer in species and more plentiful near the equator. In the ocean, that holds true for cold-blooded predators(掠食者). But warm-blooded predators are more diverse toward the poles and noticeably missing from several warm hot spots. Why?
John Grady, an ecologist, and his team considered the possibility—warm-blooded animals need a lot to fuel their metabolism(新陈代谢). Perhaps colder waters are just richer in small fish? But they found that at higher, colder places, there isn’t actually much more food around. It’s more that warm-blooded animals are eating a much bigger share of it than their cold-blooded competitors.
The real explanation is simple. An animal’s speed, swiftness, and intelligence depend on its metabolism, which in turn depends on its temperature. Since birds and mammals can keep heating their bodies in icy conditions, they remain fast and attentive. By contrast, the fish they hunt become slower and duller. At some tipping point of temperature, seals, dolphins, and penguins start outswimming their prey(猎物). They become more likely to come upon targets and outpace the cold-blooded predators of their own.
In Grady’s words, “Warm-bodied predators are favoured where preys are slow, stupid and cold.” That’s why sharks and other predatory fish dominate near the equator, but colder waters are the kingdom of whales and seals. By keeping food to themselves in the poles, these creatures can then specialize on specific types of prey, which makes them more likely to split into separate species. The killer whales of the North Pacific, for example, include mammal-eating transients and fish-eating, year-round residents.
But the world is changing. It’s likely that the surface of the oceans will warm by 2 to 3℃ within this century. Grady’s team estimates that every time the ocean’s surface warms by 1℃, populations of sea mammals will fall by 12%, and populations of seals and sea lions will fall by 24%.
But “predictions are hard,” Donna Hauser from the University of Alaska Fairbanks notes. “Polar bears are losers of a warming world, but some populations are still doing well. Some groups of whales have changed the timing of their migrations; others are hunting in deeper, colder waters. These changes might make sea mammals more adaptable to changing climates. Maybe they just need to find the places where fish remain slow, stupid and cold.”
1.Why are there more types of warm-blooded predators near the poles?
A. Because there is more food.
B. Because there are fewer enemies.
C. Because they are faster and wiser.
D. Because they consume less energy.
2.The author mentions the killer whales to show ______.
A. the benefit of biological evolution
B. food preference of different sea mammals
C. the distinction of specific types of predators
D. the advantage of constant body temperature
3.What is Donna Hauser’s attitude towards the future of the sea mammals?
A. Positive. B. Negative.
C. Neutral. D. Sceptical.
4.Which is the best title for the passage?
A. Are the Poles Heaven for Sea Predators?
B. How Do Sea Mammals Track Their Prey?
C. Why Do the Warm-Blooded Like Food Cold?
D. Is the World Too Hot for the Warm-Blooded?
In the short time Steve and Zach had been inside their tent packing their tools, wind-blown flame had skipped from the top of one tree to another. The long dry summer had turned the forest into a tinderbox.
“Let’s go! We can make it back to the river we crossed today!” Steve kept Brady on the lead and their heads down against the fire-wind. But Brady barked a sharp warning. Ahead of them lay a thick curtain of smoke across the track. They would never make it through that. The dog was pulling at his lead trying to draw them away from the smoke, and yet Steve was uneasy. It seemed to him that they were moving away from the river.
Suddenly, Zach cried. “Zach!” Steve shouted. “Are you OK? Where are you?” Then Brady pulled Steve down a sharp slope(坡). At its base, Zach was rubbing his ankle.
As Steve helped his friend to his feet, Brady lifted his head and snuffed(嗅) the smoke-laden wind. Next moment, the dog bounded away and disappeared. The boys shouted for him, but he didn’t come back. Steve couldn’t blame Brady for panicking. He himself wanted to run even though he didn’t have a clue which way.
Steve and Zach hadn’t gone far when there was a familiar bark, and Brady came bounding, stopped directly in front of Steve and hit him with his head, pushing him back toward the slope they’d just climbed. But Steve didn’t get it. Then Brady grabbed the boy’s jeans and started pulling. The message was clear, but Steve hesitated. Of course he remembered Brady saving his uncle’s life when the dog was much younger. Was he still sharp enough to get them through this?
Nearby, a pine went up in a whoosh of smoke. Brady pulled again, urgently. “OK, big guy,” Steve gritted(咬紧牙关). Brady led them back down the slope and into the trees. Not far from them fire was touching underbrush. Several times the big dog stopped. Often he changed directions. Steve was so tired that he just wanted to rest, but Brady wouldn’t have it. The dog bullied both boys to go on. How long they’d walked Steve had no idea. He was almost numb when he heard it—the wonderful sound of rushing water!
1.What happened to Steve and Zach at first?
A. They got injured. B. They lost their dog.
C. They were trapped. D. They became separated.
2.Brady ran away to ______.
A. seek help B. find a way out
C. rescue Zach D. escape for life
3.How did Steve feel after Brady pulled his jeans?
A. Uneasy. B. Impatient.
C. Numb. D. Uncertain.
4.The passage basically describes ________.
A. an adventure B. an exploration
C. an escape game D. a training program
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During my second year in high school, I got sick and missed a few days. When I ____, I was greeted with two essays due, three days of math and history homework, plus several tests. ______ I went home from school that day exhausted, I had to stay up really late to finish them all.
The next day at school, I got a rude awakening: I’d totally forgotten to prepare for the ______ on Romeo and Juliet, which I’d take ______ my lunch hour! Worse still, I had ______ the in-class discussion and all the notes. When lunch came, I went to the English room to face my certain doom(厄运). All I could do was try to ______ on the questions I didn’t know.
As it turned out, I didn’t know the majority of the questions. I was just about to give ____ when my pencil accidentally fell and broke. Standing by the blackboard sharpening my pencil, I ______ down and there in full view lay the answer sheet for the test! What good fortune! I can kiss good-bye to all my ______ of failing the test! My heart started beating, and my brain _______, Yes! Read over the answers—quickly! This was quickly followed by another voice, No! You’ll get caught! My mind turning back and forth, Yes! No! Yes! No! …This went on for ten of the ______ seconds in my entire life.
Finally, I decided to finish the test on my own, without ______! I was satisfied with my decision but pretty ______ I had failed the test.
The next day when I walked into the English room, my great joy of having been an ____ soul changed into a wave of doom as I saw my test paper lying face down on my desk. I knew what awaited me. I stared at it a few seconds before I got up the _______ to turn it over.
You can only imagine my ______ when I learned that I had passed the test! I have never in my whole life been so happy to see my ______, a C-.
My mom says the victories that ______ the most courage are won within. Now I know ______ what she means. Now not only can my conscience(良心) rest easy, but I don’t have to worry about getting caught and meeting a sad ______ like Romeo and Juliet.
1.A. arrived B. returned C. appeared D. finished
2.A. If B. Because C. Until D. Although
3.A. lecture B. essay C. play D. test
4.A. by B. upon C. over D. toward
5.A. missed B. carried C. lost D. dropped
6.A. depend B. agree C. guess D. improve
7.A. in B. off C. out D. away
8.A. wrote B. settled C. calmed D. looked
9.A. boredom B. worries C. loneliness D. tiredness
10.A. whispered B. warned C. persuaded D. chanted
11.A. coldest B. saddest C. longest D. fastest
12.A. suffering B. checking C. cheating D. thinking
13.A. certain B. regretful C. annoyed D. relieved
14.A. open B. honest C. optimistic D. energetic
15.A. wisdom B. encouragement C. intention D. nerve
16.A. anxiety B. shock C. fear D. appreciation
17.A. paper B. credit C. rate D. grade
18.A. take B. put C. find D. gain
19.A. gradually B. exactly C. willingly D. seemingly
20.A. film B. fact C. ending D. love
Going to museums has become a trendy thing to do during the holidays in China. A popular choice this Spring Festival was the Palace Museum, 1. a special exhibition was staged to provide a virtual royal experience for visitors. The entire museum 2. (decorate) with newly-restored ancient royal lanterns and spring couplets, including a set of the Chinese character “Fu” 3. (write) by five Qing Dynasty emperors.
Food is one of the most basic and important daily needs. It gives us the strength and energy we need 1. (work) and play. Food also plays a role in our social interactions. Whether we 2. (celebrate) important occasions or just relaxing with friends, eating is an important social pastime. It is also an important part of our culture. 3. a particular people like to eat can tell us a lot 4. a country’s geography, history and traditions.
