单项选择题


Questions 4 to 7 are based on the following conversation. At the end of the conversation, you will be given 20 seconds to answer the questions.
Now listen to the conversation.
Why is it difficult to predict the weather for in advance for Autumn

A.Some forecasting machines do not work well in hot weather.
B.The weather patterns are more changeable in the autumn.
C.Experts spend less time studying autumn.
D.The National Weather Service misplaced its spring and summer data.