四级练习2013.09.05
[audio]http://sound.yywz123.com/tingbbs/cet4/cet420130905.mp3[/audio]Astronomers have found numerous other black holes throughout the galaxy, but they've never seen one as it formed. NASA scientist Kimberly Weaver points out that that (1)__________________________to observe the birth and early growth of one of the most mysterious objects in the sky.
"What is it that really matters in terms of this result? It's not just that possibly we've found the youngest nearby black hole. It is a young black hole but what's really exciting about it is that we know (2)__________________________. We've found for the first time possibly the true birth date of a black hole."
And, as astronomers continue to study this object, they expect to gain new insight into (3)__________________________. The scientists discussed their work at a NASA news conference in Washington.
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