China has just opened its FAST radio telescope(射電望遠(yuǎn)鏡)to international scientists. It means scientists across the world can apply for using the telescope to do astronomical observations.

　　FAST is short for Five-hundred-meter Aperture Spherical radio Telescope. It was completed in September2016 and it officially began operating in January 2020.Measuring 500 meters in diameter. FAST is the world's largest single-dish radio telescope, and is 10 times more sensitive than the 100-meter Radio Telescope Effelsberg in Germany.

　　The major scientific task of the telescope is the observation of pulsars(脈沖星).The study of pulsars can help to confirm the existence of gravitational radiation(引力輻射) and black holes, and help solve many other major questions in physics. Another major scientific goal of FAST is to search for life outside the Earth.

　　The telescope is located in a naturally deep and round karst depression(喀斯特洼地)in southwest China's Guizhou Province. The first advantage of the selected site is the altitude(海拔).The average altitude of Guizhou is about1,100 meters. Generally,the higher the altitude,the more the telescope can observe. Secondly,the radio telescope needs to have a"big pan"to receive better signals. The huge natural depression could reduce the difficulty of construction. Moreover, the selected site in Guizhou is far away from cities, and has a low population density,which reduces the interference(干擾) caused by wireless devices such as TVs, mobile phones and radios from human activities.

　　So far, FAST has found over 300 pulsars.Experts predict that the number could reach 1,000 in five years and that the telescope could find and locate the first pulsar outside the Galaxy.

　　1.Who can use FAST?

　　A.Chinese scientists.

　　B. Scientists from all countries.

　　C.Soldiers and policemen.

　　D.All Chinese citizens.

　　2. When did FAST start working officially?

　　A. In 2015. B. In 2016.

　　C. In 2020. D. In 2021.

　　3.Which of the following is a main task of FAST?

　　A. To study black holes.

　　B. To explore the sun.

　　C. To observe pulsars in the universe.

　　D. To send signals into space.

　　4.What do we know from the fourth paragraph?

　　A. The advantages of the selected site for FAST.

　　B. Guizhou Province has the highest altitude in China.

　　C.The reasons for using mobile phones less.

　　D. FAST is built in a pan-shape place to keep people out.

　　5.What do scientists think FAST will probably be able to do in the future?

　　A. Identify more than 300 pulsars in five years.

　　B. Discover the first pulsar outside the Galaxy.

　　C. Locate wireless devices around the world.

　　D. Collect all kinds of sounds in space.
 

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