阅读理解Nowsatellitesarehelpingtoforec

阅读理解Now satellites are helping to forecast the weather. They are in space, and they can reach any part of the world. The satellites take pictures of the atmosphere（大气）, because this is where the weather forms. They send these pictures to the weather stations. So meteorologists（气象学家）can see the weather of any part of the world. From the pictures, the scientists can often say how the weather will change.
Today, nearly five hundred weather stations in sixty countries receive satellite pictures. When they receive new pictures, the meteorologists pare them with earlier ones. Perhaps they may find that the clouds have changed during the last few hours. This may mean that the weather on the ground may soon change, too. In their next weather forecast, the meteorologists can say this.
So the weather satellites are a great help to the meteorologists. Before satellites were invented, the scientists could forecast the weather for about 24 or 48 hours. Now they can make good forecasts for three or five days. Soon, perhaps, they may be able to forecast the weather for a week or more ahead（提前）1.Satellites travel______.
A.in spaceB.in the atmosphereC.above the groundD.above space2.Why do we use the weather satellites to take pictures of the atmosphere? Because ______.
A.the weather satellites can do it easilyB.clouds form in the atmosphere thereC.the weather forms in the atmosphereD.the pictures can forecast the weather3.Meteorologists forecast the weather______.
A.when they have received satellite picturesB.after paring the pictures with earlier onesC.before they received satellite picturesD.while they study satellite pictures4.The main idea of this passage is that satellites are now used in______.
A.taking pictures of the atmosphereB.receiving pictures of the atmosphereC.doing other work in many waysD.weather forecasting to the pictures