Now satellites are helping to forecast（预报）the weather. They are in space, and they can rea

Now satellites are helping to forecast（预报）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（形成）. 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（比较）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）.
【小题1】Satellites travel     .A．in spaceB．in the atmosphere C．above the groundD．above space【小题2】 Why do we use the weather satellites to take pictures of the atmosphere? Because     .A．the weather satellites can do it easilyB．clouds form thereC．the weather forms thereD．the pictures can forecast the weather【小题3】Meteorologists forecast the weather     .A．when they have received satellite picturesB．after they have pared new satellite pictures with earlier onesC．before they received satellite picturesD．during they study satellite pictures【小题4】The main（主要的）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 forecastingA