銆€銆€Black holes

銆€銆€Most scientists agree that black holes exist but are nearly impossible to locate. A black hole in the universe is not a solid object,like a planet ,but it is shaped like a sphere(鐞冮珨). Astronomers(澶╂枃瀛�(xu茅)瀹�) think that at the center of a black hole there is a single point in space with infinite(鐒￠檺鐨�) density(绋犲瘑). This single point is called a singularity(濂囬粸(di菐n)). If the singularity theory is correct ,it means that when a massive star collapses,all the material in it disappears into the singularity. The center of a black hole would not really be a hole at all, but an infinitely dense point. Anything that crosses the black hole is pulled in by its great gravity.

銆€銆€Although black holes do exist, they are difficult to observe. These are the reasons

銆€銆€No light or anything else comes out of back holes. As a result,they are invisible to a telescope

銆€銆€In astronomical terms, black holes are truly tiny. For example, a black hole formed by the collapse of a giant star would have an event horizon(瑕栫晫) only 18 miles across.

銆€銆€The nearest black holes would be dozens of light years away from Earth. One light year is about 6 trillion(钀剟) miles. Even the most powerful telescopes could not pick out an object so small at such a great distance.

銆€銆€In 1994 the Hubble Space Telescope provided evidence that black holes exist. There are still answers to be found, however, so black holes remain one of the mysteries of the mysteries of the universe.

銆€銆€16 Black holes are part of space.

銆€銆€A Right B Wrong C No mentioned

銆€銆€17 Black holes exist but are difficult to observe.

銆€銆€A Right B Wrong C No mentioned

銆€銆€18 The center of a black holes is empty.

銆€銆€A Right B Wrong C No mentioned

銆€銆€19 The attraction of two large stars leads to gravity.

銆€銆€A Right B Wrong C No mentioned

銆€銆€20 The sun is the heaviest star in the universe.

銆€銆€A Right B Wrong C No mentioned

銆€銆€21 The nearest black holes are hundreds of light years away from us.

銆€銆€A Right B Wrong C No mentioned

銆€銆€22 The Hubble Space Telescope helps scientists to understand the nature of the universe.

銆€銆€A Right B Wrong C No mentioned

銆€銆€鍙冭€冪瓟妗�锛欰 A B C C B A

銆€銆€绛旀瑙ｆ瀽锛�

銆€銆€16 A 绗竴娈电浜岃棣栧彞a black hole in the universe???鎸囨槑鏈绛旀銆傛湰椤屼腑space 涓嶆槸绌洪枔锛岃€屾槸瀹囧畽銆佸お绌虹殑鎰忔€� 锛岃窡瑾叉枃涓璾niverse鍚岀京銆�

銆€銆€17 A 绛旀鍦ㄧ浜屾绗竴鍙ヨ┍閲岋細Although black holes do exist, they are difficult to observe銆�

銆€銆€18 B 閫欏€�(g猫)闄宠堪鏄尟(cu貌)瑾ょ殑銆傜涓€娈电涓夎鐨勫彞瀛恆stronomers think that at the center of a black hole there is a single point in space with infinite density銆傚ぉ鏂囧(xu茅)瀹惰獚(r猫n)鐐洪粦娲炰腑蹇冩湁鍊�(g猫)瀵嗗害鐒￠檺澶х殑榛�(di菐n)锛屾墍浠ラ粦娲炲苟涓嶆槸绌虹殑銆�

銆€銆€19 C 闂�(gu膩n)浜巊ravity(閲嶅姏)鏄€庝箞褰㈡垚鐨�锛屾枃绔犱腑娌掓湁鎻愬埌銆�

銆€銆€20 C 閫欏€�(g猫)鍟忛鈥曗€曞お闄芥槸瀹囧畽涓渶閲嶇殑鏄熺悆鈥曗€曟枃绔犱腑涔熸矑鏈夋彁鍒�銆�

銆€銆€21 B 绗簩娈电郸鍑虹殑绗笁鍊�(g猫)鍘熷洜the nearest black holes would be dozens of light years away from Earth琛ㄦ槑闆㈡垜鍊戞渶杩戠殑榛戞礊鏈塪ozens of(瑷卞锛屽ソ骞炬墦)鑰屼笉鏄痟undreds of(鎴愮櫨涓婂崈鐨�)鍏夊勾锛屾墍浠ユ湰椤屾弿杩伴尟(cu貌)瑾�銆�

銆€銆€22 A 鏈€鍚庝竴娈电涓€鍙ュ憡瑷存垜鍊慔ubble Space Telescope provided evidence that black holes exist鍝堝媰鏈涢仩(yu菐n)閺℃彁渚涗簡榛戞礊瀛樺湪鐨勮瓑鎿�(j霉)锛屾鏄€氶亷閫欑ó鏂瑰紡锛屽搱鍕冩湜閬�(yu菐n)閺″公鍔╃瀛�(xu茅)瀹跺€戞洿濂藉湴浜嗚В浜嗗畤瀹欑殑鏈唱(zh矛)銆傚洜姝よ┎闄宠堪姝ｇ⒑銆�