第20页

How Sharks Follow Their Nose to Their Next Meal 鲨鱼运用自己的嗅觉来觅食
听力原文
Few creatures on earth are as good as sharks at finding their dinners. People often say that a shark follows its nose to its meals. Now, scientists have learned more about how those noses work to help the much-feared fish direct its movements.

Recently published research questions a common belief about sharks.

Some people think that sharks simply follow the strongest smells that reach them to find their prey, or target. But scientists now can show that differences between the times when a shark’s nostrils receive smells is more important than the strength of the odors.

Researchers Jayne Gardiner and Jelle Atema reported their findings in the publication Current Biology.

Scientists have found that differences between the time when a shark’s nostrils receive smells is more important than the strength of the odors.

The researchers studied small sharks called smooth dogfish, common to America’s New England coast. The animals were swimming in a tank or container.

The scientists placed special equipment on the sharks to direct odors directly to their nostrils. The smells were from squids—a favorite meal of the smooth dogfish shark.

Then the scientists watched and recorded which way the sharks turned to follow the odor.

Ms. Gardiner said the delay between the arrival of the smell at each nostril could be as little as a half second or less. The animals turned and swam in the direction of the nostril that first received the odor. Ms. Gardiner said this was true even if the odor in the second nostril was stronger.

Following the odor received by the first nostril guided the sharks into smelly areas in the water. The fish then followed the odors to the squid.

知识点睛
1. But scientists now can show that differences between the time when a shark’s nostrils receive smells is more important than the strength of the odors.

本句是一个复合句。that 引导的从句作show 的宾语；when a shark’s nostrils receive smells is more important than the strength of the odors 是定语从句，修饰the time 。

2. Ms. Gardiner said this was true even if the odor in the second nostril was stronger.

本句是一个复合句。this was true even if the odor in the second nostril was stronger 是一个宾语从句，作said 的宾语；其中even if the odor in the second nostril was stronger 是一个让步状语从句。


How Changes on the Sun Can Affect Our Climate 太阳表面变化怎样影响地球气候
听力原文
An American study has shown a link between activity on the surface of the sun and weather conditions on Earth. Scientists say small changes in the sun’s brightness can produce effects on Earth similar to two weather events in warm waters of the Pacific Ocean. The two events are commonly known as La Nina and El Nino. Reports say the study may lead to better predictions of temperatures, rainfall and the intensity of weather systems.

Scientists measure solar activity by counting dark areas on the sun’s surface. These sun spots produce bursts of energy. Other scientists have shown that sun spot activity can be measured in periods of time that last about eleven years. The total energy reaching Earth from the sun rises and falls by just one tenth of one percent across this solar cycle.

In the new study, scientists examined more than one hundred years of ocean temperature records. They also used computer programs designed to reproduce the world’s climate. They found the highest levels of solar activity cause small, but far-reaching effects on weather systems around the world. These periods of high activity are known as solar maximum.

Gerald Meehl was the lead writer of a report about the study. He says his team showed the effects of a new process to understand what happens in the Pacific’s warm waters where there is a maximum of solar activity. Professor Meehl works for the National Center for Atmospheric Research in Boulder, Colorado. The center organized and helped to pay for the study. The findings were published recently in the Journal of Climate.

知识点睛
1. produce effects on

短语，意思是“对……发生影响”。例：Renal diseases produce greater effects on the kinetics of drugs with a high fraction excreted unchanged.

肾脏疾病对高原型排泄分数药物的代谢动力学影响较大。

2. Other scientists have shown that sun spot activity can be measured in periods of time that last about eleven years.

本句是一个复合句。that sun spot activity can be measured in periods of time that last about eleven years 是一个宾语从句，作shown 的宾语；that last about eleven years 是一个定语从句，修饰periods of time 。



Backyard Astronomers Discover Black Holes and Other Wonders 后庭天文学家发现黑洞和其他天文奇观
听力原文
Johnson likes the quiet and he likes the dark. But clouds and sub-zero temperatures are working against him as he stargazes near his home in Western Maryland.

Johnson has been stargazing for 50 years, and tonight he’s invited some kids to join him. He has a near photographic memory of hundreds of star positions and he loves to share what he knows.

Johnson is the maintenance man at Deep Creek’s Lake Nature Center. He’s also an avid reader of Sky and Telescope magazine. In 1979, he was featured there—for discovering a supernova that scientists now believe is the newest and nearest black hole.

Backyard astronomers have been making discoveries for centuries dating back to Galileo, whom amateurs claim as one of their own. His degree was in art. The famous Comet Hale-Bopp was discovered in 1995 by two amateurs, one of whom did not even own a telescope. He was using a friend’s. And in 2007, volunteers in an online astronomy project discovered the “green pea” galaxies, so-named because they appear small and greenish in images.

Astrophysicist Kim Weaver was part of the NASA team that announced last month that Gus Johnson’s supernova, or exploding star, was likely the birth of a black hole, a region in space where nothing can escape, not even light.

Scientists believe that black holes are born often in the universe. But to actually see it happen, well that’s a story.

When Johnson spotted the star more than 30 years ago, he put out an alert, and telescopes including NASA’S powerful Chandra X-Ray Observatory have been watching it ever since.

We caught up with Weaver at the Goddard Space Flight Center in Maryland where she works.

Two years ago, at age 14, she made a major discovery, not with a telescope but with a computer, scanning hundreds of photos as part of an online search team.

Moore says supernova hunting is competitive. Back in Maryland, Gus Johnson observes fresh-fallen snow and an iced-over

Deep Creek Lake. There’s something almost sad about his intense love of the environment, even with its fleeting nature.

But his discovery, that he holds onto.

Johnson wasn’t looking for a supernova that night, it was entirely accidental. But, now he looks for them.

知识点睛
1. He has a near photographic memory of hundreds of star positions and he loves to share what he knows.

本句是一个复合句。and 连接两个并列分句；后一个分句中，what he knows 是一个宾语从句，作share 的宾语。

2. In 1979, he was featured in the magazine—for discovering a supernova that scientists now believe is the newest and nearest black hole.

本句是一个复合句。for discovering a supernova that scientists now believe is the newest and nearest black hole 是一个介词结构作原因状语；that scientists now believe is the newest and nearest black hole 是一个定语从句，修饰a supernova 。

3. Astrophysicist Kim Weaver was part of the NASA team that announced last month that Gus Johnson’s supernova, or exploding star, was likely the birth of a black hole, a region in space where nothing can escape, not even light.

本句是一个复合句。that announced last month that Gus Johnson’s supernova, or exploding star, was likely the birth of a black hole, a region in space where nothing can escape, not even light 是一个定语从句，修饰the NASA team ；其中that Gus Johnson’s supernova, or exploding star, was likely the birth of a black hole, a region in space where nothing can escape, not even light 是一个宾语从句，作announced 的宾语；a region in space 是a black hole 的同位语；where nothing can escape, not even light 是一个定语从句，修饰a region 。



Wolverines Stage a Comeback 密西根狼獾卷土重来
听力原文
One of the rarest mammals in North American is staging a comeback in the mainland United States. Wildlife biologists have tracked wolverines on mountainsides where they haven’t been seen in many decades. But several new studies suggest the recovery could be short-lived if the animals’ mountain snowline habitat continues to retreat due to global warming.

If you’re willing to settle for a mascot, the legendary wolverine is easy to find in the USA. It’s the namesake of countless high schools, a bunch of colleges and several American university sports teams. But if you want to see an actual wolverine in the wild, good luck. Despite the fact that the brown, shaggy carnivores are among the largest members of the weasel family and reach weights up to 15 kilograms, these stocky scavengers are extremely elusive. The scientists who study them rely on radio tracking technology and aircraft or snowmobiles to improve the odds of finding their quarry.

John Rohrer, a district biologist for the Okanagan-Wenatchee National Forest, also uses dead deer heads to lure elusive wolverines. “They’re in this winter environment that we think is so harsh and so inhospitable, and they’re loving it.”

Rohrer, Scott Fitkin and company have set up 11 live capture traps in the high country east of the Cascade Crest. Both men have worked with all sorts of interesting critters, but hold a special reverence for the wolverine.

They’re also really rare. Trapping and deliberate poisoning more or less wiped out the wolverine from the contiguous United States. But now wolverines have moved down from Canada to reoccupy their historic ranges.

This is the sixth season Rohrer and Fitkin have pursued the elusive scavengers. Captures are rare. Fitkin videotaped the most recent one of a wolverine they named Rocky.

When the field crew catches a wolverine, they attach a GPS tracking collar and set the animal free again. Study leader Keith Aubry can monitor the signals from his desk at the Forest Service’s Pacific Northwest Research Station in Olympia.

The Forest Service is funding a parallel study in central Idaho. But in Idaho, the wolverines aren’t the only ones being tracked. The research team led by biologist Kim Heinemeyer is asking snowmobilers and backcountry skiers to voluntarily carry GPS tracking units, too. That lets Heinemeyer see whether human recreation affects the wolverines.

知识点睛
1. But several new studies suggest the recovery could be short-lived if the animals’ mountain snowline habitat continues to retreat due to global warming.

本句是一个复合句。the recovery could be short-lived if the animals’ mountain snowline habitat continues to retreat due to global warming 是一个从句，作suggest 的宾语；其中if the animals’ mountain snowline habitat continues to retreat due to global warming 是由if 引导的条件状语从句；due to global warming 是一个介词结构作状语，表原因。

2. Despite the fact that the brown, shaggy carnivores are among the largest members of the weasel family and reach weights up to 15 kilograms, these stocky scavengers are extremely elusive.

本句是一个复合句。Despite the fact that the brown, shaggy carnivores are among the largest members of the weasel family and reach weights up to 15 kilograms 是介词结构作让步状语；其中that the brown, shaggy carnivores are among the largest members of the weasel family and reach weights up to 15 kilograms 是同位语从句，作the fact 的同位语。

3. The biologists who study them rely on radio tracking technology and aircraft or snowmobiles to improve the odds of finding their quarry.

本句是一个复合句。who study them 是定语从句，修饰the biologists；to improve the odds of finding their quarry 是不定式结构作状语，表目的。