Directions: There is a passage in this part. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A),B),C) and D).You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the center. Some radio singals were heard in 1967.They were coming from a point in the sky where there was unknown star.They were coming very regularly,too:about once a second,if they were controlled by clock. The scientists who heard the signals did not tell anybody else.They were rather afraid to tell in case they frightened people.The signals were coming from a very small body—no bigger,perhaps than the earth.Was that why no light could be seen from it?Or were the signals coming from a planet that belonged to some other star? There was no end to the questions,but the scientists kept the news secret.“Perhaps there are intelligent beings out there.”they thought,“who are trying to send messages to other planets,or to us?So the news was not given to the newspaper.Instead,the scientists studied the signals and searched for others like them...Well,all that happened in 1967 and 1968.Since then scientists have learnt more about those strange,regular,radio signals.And they have told the story,of course. The signals do not come from a planet;they come from a new kind of star called a “pulsar””.About a hundred other pulsars have now been found,and most of them are very like the first one. Pulsars are strong radio stars.They are the smallest but the heaviest stars we know at present.A handful of pulsar would weigh a few thousand tons.Their light—if they give much light—is too small for us to see.But we can be sure of this,no intelligent beings are living on them.