共用题干

共用题干
Black Holes

1 Black holes can be best described as a sort of vacuum,sucking up everything in space.Scientists
have discovered that black holes come from an explosion of huge stars.Stars that are near death can no longer
burn due to loss of fuel , and because its temperature can no longer control the gravitational（重力的）force,
hydrogen ends up putting pressure onto the star's surface until it suddenly explodes then collapses.
2 Black holes come from stars ihat are made of hydrogen,other gases and a few metals.When these
explode it can turn into a stellar-mass（恒星质量) black hole , which can only occur if the star is large enough
(should be bigger than the sun)for the explosion to break it into pieces,and the gravity starts to compact
every piece into the tiniest particle.Try to see and compare:if a star that's ten times the size of the sun ends
up being a black hole that's no longer than 70 kilometers,then the Earth would become a black hole that'S
only a fraction of an inch!
3 Objects that get sucked in a black hole will always remain there,never to break free.i1it remember
that black holes can only gobble up（吞噬）objects within a specific distance to it.It's possible for a large
star near the sun to become a black hole,but the sun will continue to stay in place.Orbits（轨道）do not
change because the newly formed black hole contains exactly the same amount of mass as when it was a star,
only this time its mass is totally contracted that it can end up as no bigger than a state.
4 Sofar,astronomers have figured out that black holes exist because of Albert Einstcin's theory of
relativity.In the end,through numerous studies,they have discovered that black holes truly exist.Since black
holes trap light and do not give off light,it is nearly impossible to detect black holes via a telescope.But
astronomers continue to study galaxies（银河系）, space and the solar system to understand how black holes
might evolve.It is possible that black holes can exist for millions of years,and later contribute to a bigger
process in galaxies,which can eventually lead to creation of new entities（实体）.Scientists also credit black
holes as helpful in learning how galaxies began to form.

Albert Einstein's theory of relativity helps to prove__________.
A:the existence of black holes
B:the creation of new entities
C:the same amount of mass
D:an fraction of an inch
E:a fraction of an inch
F:the tiniest particle