Nowadays meteorologists can make good forecast for 3 or 5 days ．Perhaps soon they may be able to do that for a week or ____．

A．more behind       B．more ahead           C．less behind          D．less ahead

．Nowadays meteorologists can make good forecast for 3 or 5 days ．Perhaps soon they may be able to do that for a week or ____．

         A．more behind    B．more ahead             C．less behind     D．less ahead

．Nowadays meteorologists can make good forecast for 3 or 5 days ．Perhaps soon they may be able to do that for a week or ____．

       A．more behind  B．more ahead   C．less behind     D．less ahead

．Nowadays meteorologists can make good forecast for 3 or 5 days ．Perhaps soon they may be able to do that for a week or ____．

完形填空

阅读下面短文，掌握其大意，然后从1－20各题所给的四个选项(A、B、C和D)中选出最佳选项。

　　Nowadays, satellites are helping to forecast(预报) the weather. They are in space, and they can reach any 1 of the world. The satellites 2 pictures of the atmosphere, because this is 3 the weather forms. They send these pictures to the weather stations, 4 meteorologists(气象学家) can see the 5 of any part of the world. From the pictures, the scientists can 6 say how the weather will change. 7 , nearly five hundred weather stations in sixty counties receive satellite pictures. 8 they receive new pictures, the meteorologists compare them with the 9 ones. Perhaps they may find that the clouds 10 during the last few hours. This may 11 that the weather on 12 may soon change, too. In their 13 weather forecast, the meteorologists can say this. The weather satellites 14 for other work. So satellites are a great 15 to the meteorologists. Before satellites were 16 , the scientists could forecast the weather 17 about 24 or 48 hours. Now they can 18 good forecasts for three or five days. 19 , perhaps, they may be able to forecast the weather for a week or more 20 .

　　It is no doubt that satellites can be used in many other fields in science now.

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