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Is human hibernation possible?
Black bears hibernate to get through winter.
W___1___ low temperatures and a lack of food, winter is a harsh season for animals. Many animals enter hibernation to get through it.
Hibernation is w____2____ an animal goes into a state of extended inactivity. Animals hide away from predators. Their metabolism will slow to less than a quarter of its normal rate. This cools the creature’s body and slows its heartbeat to just a few t____3____ per minute, for up to months at a time.
But why don’t humans hibernate? Human hibernation doesn’t exist for many reasons. Our body is not d____4____ for hibernation. Our evolutionary ancestors were tropical animals with no history of hibernating: Humans have only migrated into temperate and subarctic latitudes in the last hundred thousand years or so. That’s not quite long enough to evolve al
l the metabolic adaptations we would need to be able to hibernate, according to the BBC Science Focus Magazine.
For example, waste management is a huge c____5____ for human hibernation. Animals that hibernate are able to essentially stop their urination (排尿) and defecation (排便) during hibernation, sometimes through a process of reabsorption to preserve nutrients. Unfortunately, humans can’t do this.
There are other challenges. Body temperatures below 2.8 C tend to disrupt the human digestive tract and may cause pain. C____6____ temperatures can also suppress the immune system, making people more vulnerable to infections, according to Smithsonian Magazine.
In fact, humans don’t need to sleep through winter. We have discovered fire, clothes, shelter, hunting and agriculture, all of which are much more effective w____7____ of surviving the cold.
Could humans hibernate in the future? For long-distance space travel, it’s l____8____. A journey to Mars would take around months using current technology. If we hope to visit another star system, even if we could travel at the speed of light, the journey would t____9____ years. Being able to hibernate would make such distances considerably less boring for the astronauts and conserve vital resources, according to University of Oxford in the UK.
NASA is treating this question seriously. Beginning in 2014, the agency funded research on long-term hibernation as a way to facilitate long-term space travel, according to The Atlantic magazine.
1. with        2. when        3. times        4. designed    5. challenge       
6. Cold        7. ways        8. likely        9. take    hibernating   
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Whales are huge, but difficult to see, which a___1___ to their mystery and fascination. Th
ey are highly intelligent animals with a carefully-organized social life.
Blue whales are difficult to w___2___ because of their size, at up to 200 tons, even an ordinary-sized whale is a vast and impressive creature. Their tongues can weigh as much as an elephant: their hearts weigh as much as an automobile. Quite a size!
As their names s___3___, blue whales look true blue underwater, but on the surface their color is more like blue-gray. Their underbellies take on a yellowish color.
Blue whales live in all the world’s oceans, occasionally swimming in small g___4___, but usually alone or in pairs. These graceful swimmers travel through the ocean a___5___ more than five miles an hour but accelerate to more than 20 miles an hour when they are angry. Blue whales are among the l___6___ animals on the planet. They emit a series of pulses and sounds, and it’s thought that, in good conditions, blue whales can hear each other up to 1,000 miles away. Scientists think that they use these m___7___ not only to communicate, but, along with their excellent hearing, to navigate the lightless ocean depth.
1. adds    2. weigh    3. suggest    4. groups    5. at    6. loudest
7. methods
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The White House of America
The White House is one of the world’s most famous b___1___. For more than two hundred years, the White House has been more than just the home of the Presidents and their families. It has stood as a s___2___ of being President, of the United States g___3___ and of the American people. At various times in history, the White House has been k___4___ as the “President’s Palace”, the “President’s House”, and the “Executive Mansion”(行政官邸). President Theodore Roosevelt officially gave the White House its current name in 1901.
The White House includes special sections for public visits and p___5___family sections that are just for the family. The president’s office, for example, is in the West Wing of the b
uilding. Above the Oval(椭圆的)Office are the private family sections, where the present President Obama and his family have dinner t___6___ nearly every night.
Each year about 15 million people visit the White House. As a v___7___ , you can walk on the White House lawns, go through its halls and even sample(品尝) a meal from its kitchen! With five full-time cooks, the White House kitchen is able to serve dinner to as many as 140 g___8___.
It takes a lot of people to keep the White House running—about 1,700 to be exact! These employees do everything f___9___ cooking to answering phones to taking photos to arranging flowers to decorating the place for Christmas each year. There are official White House electricians(电工), servants, cooks, secretaries and even librarians.

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