题型:阅读理解 题类:常考题 难易度:普通
四川省绵阳市2018-2019学年高一下学期英语期末考试试卷(含小段音频)
Astronomers have taken the first ever image of a black hole, which is located in a distant galaxy (星系).The black hole is 500 million trillion km away and was photographed by a network of eight telescopes across the world. It was captured by the Event Horizon Telescope (EHT).
The announcement was made in Washington, Brussels, Santiago, Shanghai, Taipei and Tokyo. Details have been published today in Astrophysical Journal Letters.
Prof Heino Falckc, of Radboud University in the Netherlands, who suggested the experiment, told BBC News that the black hole was found in a galaxy called M87. "What we see is larger than the size of our entire Solar System," he said. "It has a mass 6.5 billion times that of the Sun. And it is one of the heaviest black holes that we think exists. It is an absolute monster, the heavyweight champion of black holes in the Universe."
The image shows an intensely bright "ring of fire", as Prof Falckc describes it, surrounding a perfectly circular dark hole. The bright halo is caused by very heated gas falling into the hole. The light is brighter than all the billions of other stars in the galaxy combined - which is why it can be seen at such distance from Earth. The edge of the dark circle at the center is the point at which the gas enters the black hole, which is an object that has such a large gravitational pull (万有引 力),not even light can escape.
"It is remarkable that the image we observe is so similar to that which we get from our theoretical calculations. So far, it looks like Einstein is correct once again." said Dr Ziri Younsi, of University College London -who is part of the EHT cooperation.
Chinese scientists were involved in the observation through a telescope in Hawaii. They were also highly involved in follow-up data processing and theoretical analysis, said Shen Zhiqiang, head of the Chinese Academy of Sciences' Shanhai Astronomical Observatory and a member of the EHT international team.
Shanghai and Taipei were selected as two of the cities to hold news conferences, together with Washington, Brussels, Santiago and Tokyo, a recognition of China's contribution.
"In the fields of astronomy, radio astronomy, and space astrophysics, China has made a significant contribution to this global project," Falcke said.
Here, sleep experts clear up some of the biggest misunderstandings about sleep they see with their patients, which could weaken your ability to have a night of good sleep.
Myth: {#blank#}1{#/blank#}
The latest research shows that the right amount of sleep may vary from person to person and should leave you feeling energized the next day. I'm a sleep doctor. Take myself for example. {#blank#}2{#/blank#}.
Myth: Don't fall asleep with the TV on.
I've cured more people suffering from sleep problems than you can imagine by telling people it's OK to fall asleep with the TV on. {#blank#}3{#/blank#}Control the watching time so it doesn't affect your sleep later in the night.
Myth: You can catch up on lost sleep on the weekend.
{#blank#}4{#/blank#} A Harvard study found that even if you sleep for an extra 10 hours on the weekend to make up for only sleeping six hours a night for two weeks, those extra hours won't improve your reaction times or ability to focus. Plus, sleeping late throws off your biological clock, which can lead to obesity, diabetes, and heart disease.
Myth: Alcohol can help you rest easy.
{#blank#}5{#/blank#} Alcohol may relax you so you nod off quicker, but studies show you'll wake up more and get less of deep sleep you need to feel rested.
A. You need 8 hours' sleep a night. B. A lack of sleep can cause anxiety. C. We take unscheduled naps during the weekend. D. I've been a 6.5-hour sleeper my entire adult life. E. Many people can't turn off their brains, but watching TV helps. F. People commonly use alcohol to fall asleep, but it doesn't work. G. You can't make up for too little sleep by sleeping more at weekends. |
试题篮