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.”
(　　)28. 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.
(　　)29. What does the underlined word “probe” in Paragraph 3 possibly mean?
A. Explore.    B. Evaluate.    C. Produce.    D. Predict.
(　　)30. 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
(　　)31. 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.
28～31　CADC