1 . For years, planet-hunters have been searching for a planet other than Earth that can support life. They may have found one.

The planet is the sixth found orbiting a star called Gliese 581. Steven Vogt, one of the scientists involved, expects the new planet to have water. On Earth, when we find water, we find life.     1    

A planet that can support life has to be just the right size for its system and just the right distance from its star. Some planets orbit so close to their stars that they’re much too hot for liquid water—or for life as we know it.     2    

But a right-sized planet that's neither too close nor too far might be just right for water. Gliese 581 is probably just right. It is about three times as huge as Earth.     3     Because it’s so close, one side of it always faces its star, and the other side is always dark.

The new planet is 20 light years away, which is as far as 250 million trips to the Moon and back.     4     Only light can go that fast. So even at the fastest speed we could manage, it would take a spaceship from Earth more than 200 years to go that far.     5     But that doesn’t mean we can’t study it. Thanks to powerful new telescopes and new techniques for searching the skies, scientists can learn a lot about distant planets without even leaving Earth.

Gliese 581 is an exciting discovery—and astronomers are likely to find more soon, thanks to new, powerful telescopes specifically designed to look for planets.

A．We can’t travel at the speed of light.

B．It’s pretty hard to imagine that water wouldn't be there.

C．Human beings won’t be visiting this planet any time soon.

D．So scientists looking for life on other planets look for water first.

E．It orbits its star so closely that it goes all the way around in only 37 days.

F．Astronomers will probably find more potential life-supporting planets soon.

G．Other planets keep their distance from the stars—where they’re too cold to have water or life.

2 . The far side of the moon is a strange and wild region, quite different from the familiar and mostly smooth face we see nightly from our planet. Soon this rough space will have even stranger features: it will be crowded with radio telescopes.

Astronomers are planning to make the moon's distant side our newest and best window on the cosmic(宇宙的) dark ages, a mysterious era hiding early marks of stars and galaxies. Our universe was not always filled with stars. About 380,000 years after the big bang, the universe cooled, and the first atoms of hydrogen formed. Gigantic hydrogen clouds soon filled the universe. But for a few hundred million years, everything remained dark, without stars. Then came the cosmic dawn: the first stars flickered, galaxies came into existence and slowly the universe's large­scale structure took shape.

The seeds of this structure must have been present in the dark­age hydrogen clouds, but the era has been impossible to probe using optical(光学的) telescopes—there was no light. And although this hydrogen produced long­wavelength(or low­frequency) radio emissions,radio telescopes on Earth have found it nearly impossible to detect them. Our atmosphere either blocks or disturbs these faint signals; those that get through are drowned out by humanity's radio noise.

Scientists have dreamed for decades of studying the cosmic dark ages from the moon's far side. Now multiple space agencies plan lunar missions carrying radio­wave­detecting instruments—some within the next three years—and astronomers' dreams are set to become reality.

“If I were to design an ideal place to do low­frequency radio astronomy, I would have to build the moon,” says astrophysicist Jack Burns of the University of Colorado Boulder. “We are just now finally getting to the place where we're actually going to be putting these telescopes down on the moon in the next few years.”

1. What's the purpose of building radio telescopes on the moon?

A．To research the big bang.	B．To discover unknown stars.
C．To study the cosmic dark ages.	D．To observe the far side of the moon.

2. What does the underlined word “probe” in Paragraph 3 possibly mean?

A．Explore.	B．Evaluate.
C．Produce.	D．Predict.

3. Hydrogen radio emissions can't be detected on Earth because ________．

A．there was no light in the dark ages

B．they cannot possibly get through our atmosphere

C．gigantic hydrogen clouds no longer fill the universe

D．radio signals on Earth cause too much interference

4. What can we infer from the underlined sentence in the last paragraph?

A．Scientists have to rebuild the moon.

B．We will finally get to the moon's distant side.

C．The moon is a perfect place to set up radio telescopes.

D．A favorable research environment will be found on the moon.