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    You might have learned in your science classes that the sun is quite large and heavy. What if you heard that we’ve found a black hole that contains the mass (质量) of nearly 70 suns?

    Chinese scientists used LAMOST, a powerful Chinese telescope (望远镜), as well as telescopes in Hawaii and the Canary Islands, to make this discovery.

    According to Einstein’s theory, black holes come from dying stars. The star collapses (坍塌) into a small point with a lot of mass and strong gravity (引力). The strong gravity of the black hole allows it to pull other things in and “eat” them. Scientists search for black holes by looking at x-rays that are released when they “eat” nearby stars. However, when black holes are inactive, this method doesn’t work.

    This time, the researchers looked at stars that orbit invisible (看不见的) objects. These objects, they believe, cannot be anything but black holes. After calculating (计算) the speed of one particular star in a star system named LB-1, the scientists figured out that it was orbiting (绕轨道运行) a stellar-mass black hole.

    The black hole’s mass is about 70 times the mass of our sun. According to current theory, this black hole shouldn’t even be able to exist. It was previously believed that the mass of such a black hole cannot be bigger than that of 25 suns. Stellar (星球的) winds blow away the heavy elements that are left behind when a star dies. But somehow, this black hole kept most of its heavy elements.

    Researchers said it is possible that the black hole formed out of two large stars that died and merged (结合) together.

    The discovery is also inspiring some researchers to revisit their previous studies. “This discovery forces us to re-examine our models of how stellar-mass black holes form,” University of Florida physicist David Reitze was quoted as saying in a press release.

    1.How did Chinese scientists find the stellar-mass black hole?

    A.By looking at stars moving away from the black hole.

    B.By studying x-rays that came from the black hole.

    C.By calculating the gravity of a nearby black hole.

    D.By looking at the speed of a star that orbits it.

    2.What does the underlined word “inactive” mean in Chinese?

    A.积极的 B.不活跃的 C.快速的 D.活泼的

    3.What do we know about the black hole?

    A.It is much heavier than the sun. B.It is moving faster than the sun.

    C.It hasn’t “eaten” any stars. D.It will disappear soon.

    4.What is the last paragraph about?

    A.The importance of this discovery.

    B.Previous studies on black holes.

    C.The formation (形成?构成) of stellar-mass black holes.

    D.The preparations that were done before making this discovery.

    5.What do we know from the story?

    A.Black holes are usually heavier than 25 suns.

    B.We cannot believe current scientific theories.

    C.Black holes can form after stars die.

    D.Stellar-mass black holes contain no heavy elements.

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