【推荐1】How many things can you see in the night sky? A lot! On a clear night you might see the Moon, some planets, and thousands of stars.

But scientists believe there are some things in the sky that we will never see. We won’t see them with the biggest telescope (望远镜) in the world, on the clearest night of the year. That’s because they are invisible (看不见的). They’re the mysterious dead stars called black holes.

You might find it hard to imagine that stars die. After all, our Sun is a star. Year after year we see up in the sky, burning brightly, giving us heat and light. The Sun certainly doesn’t seem to be getting old or weak. But stars do burn out and die after billions of years.

As a star’s gases burn, they give off light and heat. But when the gases run out, the star stops burning and begins to die.

As the star cools, the outer parts of the star pull in toward the center. The star is squashed (挤压) into a smaller and smaller ball. If the star was very small, the star ends up as a cold, dark ball. If the star was very big, it keeps being squashed inward until it’s packed together tighter (紧的) than anything in the universe.

Imagine if the Earth collapsed until it was the size of a tiny marble (玻璃球). That’s how tightly this dead star, a black hole, is packed. What pulls the star in toward its center with such power? It is the same force that pulls you down when you jump – the force call gravity. A black hole is so tightly packed that its gravity absorbs everything – even light. The light from a black hole can never come back to your eyes. That’s why you see nothing but blackness.

So the next time you look up at the night sky, remember: there’s more in the sky than meets the eye! Scattered (散落) in the silent darkness are black holes – the great mystery of space.

1. What might happen after a star dies?

A．The star might become a black hole.	B．The Earth might be hit by the star.
C．The sky might become much darker.	D．The gravity might totally disappear.

2. What causes a star to die?

A．Its gases run out.	B．It hits other stars.
C．It gets too hot.	D．Its light fades away.

3. What does the underlined word “collapsed” in paragraph 6 probably mean?

A．Rolled.

B．Ran.

C．Fell inward.

D．Spread out.

4. Why are people unable to see light from a black hole?

A．Most black holes are too far away.	B．We don’t have a powerful enough telescope.
C．Black holes can travel as fast as light.	D．Light can not escape a black hole’s gravity.

【推荐2】Have you ever suddenly developed an appetite from a passing glance at a freeway billboard featuring a brightly colored cheeseburger, or decided to step into a candy or ice cream store displaying a window full of lively shades and hues (色调) of sweet treats？If so, you are in good company. Unless we are medically restricted or strictly dieting, we are not likely to resist inviting fare simply because we recognize the lack of nutritional value.

Devina Wadhera and Elizabeth D. Capaldi­Phillips in A Review of Visual Cues Associated with Food on Food Acceptance and Consumption recognize the impact of sensory cues (信号) on food consumption and enjoyment, and the potential they have to promote healthy eating behavior. They cite previous research in providing some interesting examples of the visual impact of different color schemes (方案) on taste and food enjoyment. They note that pink food on a white plate was considered sweeter and more flavorful than the same food on a black plate. Apparently, we consume food with more of our senses than we realize.

So when we’re faced with so many appealing food choices and given the rainbow of colors around us, is there any way to control our appetite? Thankfully, some research says yes.

Oliver Genschow demonstrated that when it comes to eating less, colors impact consumption. They specifically researched the effect of the color red. They found that people ate fewer pretzels when using a red plate, as opposed to white or blue, and drank less from a red cup than a blue cup. They suggested that the color red reduces food and drink intake by functioning as a stop signal.

But when it comes to healthy eating, instead of putting on a pair of sunglasses to block the inviting hues of food cues, consider the value of discipline. Healthy eating involves intentional choices, not mindless responses to sensory cues. And before you invest in much red tableware to slim down, remember that what goes onto the plates is much more important.

1. What may be a major reason for us to refuse eye­catching food?

A．The shortage of nutrition.

B．The rich color of fine foods.

C．The doctor's instructions.

D．Advertisements everywhere.

2. What might be dealt with in A Review of Visual Cues Associated with Food on Food Acceptance and Consumption?

A．Benefits of different color schemes.

B．Interesting examples of food service.

C．The potential to promote food consumption.

D．Effects of sensory cues on eating behavior.

3. What does the author suggest people do in the last paragraph?

A．Follow the sensory response.

B．Make food choices sensibly.

C．Wear sunglasses to block colors.

D．Avoid colorful food intentionally.

4. What is the best title for the text?

A．How Can People Control Their Appetite?

B．How Are People Tricked by Color Schemes?

C．How Do Colors Impact Food's Appeal and Appetite?

D．How Do Bright Colors Make Food More Appealing?

【推荐3】Running may feel like a big task for most of us. But do you know our species has evolved to run better than any other animals on this planet? Cheetahs are the fastest land animals in the world. But do you know that humans can leave them in the dust? At least, in the long run, that’s right. When it comes to endurance, we can outrun cheetahs, wolves and even horses. So what makes humans such endurance running superstars? The secret weapon is our sweat. We have 2－4 million sweat glands(腺) all over our body, which means we can run and cool ourselves at the same time. Having no fur is also a huge plus. In contrast, dogs rely on panting(喘息) to cool down, and other animals, like horses and camels, also sweat, but less effectively. As a result, they overheat faster and must slow down sooner.

So, why did humans get to be such great endurance runners, anyway? Some experts believe this became important around 2－3 million years ago, when we started hunting. Because we couldn’t chase down a gazelle(瞪羚) like a cheetah, early humans learned hunting.

Studies show running can lower body weight and body fat. And the longer you train, the greater the benefits are. Just one year of training has been shown to reduce body weight by about 7 lbs, lower body fat by 2.7% and decrease resting heart rate by 2.7%.

It may seem really hard, or even impossible to run a mile or a marathon. But in fact, you were born to go on that run. We all were.

1. In the first paragraph, cheetahs are mentioned to ________.

A．show cheetahs are the fastest land animals in the world

B．introduce humans can run fastest on the planet in the long run

C．contrast with wolves and even horses in one aspect of endurance

D．inform running may be a big challenge for most of us humans

2. Why can we humans be endurance running superstars?

A．We can pant to cool down our heat like dogs.

B．We can sweat effectively like horses and camels.

C．We have massive sweat glands and meanwhile no fur.

D．We can run and overheat fastest to cool down ourselves.

3. According to studies in the text, if you want to lose weight, what should you do?

A．Eat a variety of vegetables and less fat.	B．Work out at the gym every day.
C．Exercise outside as much as you like.	D．Conduct systematic training in running.

4. What does the author intend to emphasize in the last paragraph?

A．Humans have great running ability by birth.

B．Humans can chase down animals like cheetahs.

C．Marathoners don’t need hard training.

D．Running can lower body weight and fat.