卫星变轨运动,速度怎么变化

Now satellites(卫星)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 station. So meteorologists(气象专家)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 meteor- ologists compare(比较)them with earlier ones. Peerhaps they may find that the clouds have changed during the last few hours .This may mean 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 3 or 5 days. Soon,perhaps , they may be ablet to forecast the weather for a week or more ahead(提前)
小题1:Satellites travel__________.
A in space B in the atmosphere
C above the ground D 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 easily
B clouds form there
C the weather forms there
D the pictures can forecast the weather
小题3: Meteorologists forecast the weather________.
A when they have received satellite pictures
B after they have compared new satellite pictures with earlier ones
C before they receive satellite pictures
D while they study satellite pictures
小题4:Maybe we’ll soon be able to forecast the weather for _______.
A one day B two days C five days D seven days or even longer
小题5:The main idea of this passage is that satellite are now used in______.
A taking pictures of the atmosphere
B receiving pictures of the atmosphere
C doing other work in many ways
D weather forecasting