
动力因数D=(Ft-Fw)/G。()


Listen to a short passage three times. When the passage is read for the first time, listen for its general idea. When the passage is read for the second time, fill in the blanks with the exact words you hear. When the passage is read for the third time, check what you have written.
Some parts of the earth are more likely to have earthquakes than other parts. This is usually true of 1)________ areas because there the thickness of rocks is not even.
It is easy to understand why people are so 2)________ by earthquakes. People used to believe that when an earthquake 3)________, the ground opened, swallowed great numbers of people, and then it closed. It was also thought that those people would 4)________ forever. But now we know this is not what really happens.
What we need to fear most is the effects of a serious earthquake, including fires, floods, and landslides. A powerful earthquake 5)________ in Yellowstone National Park on August 17, 1959. The earthquake was 6)________ and very strong. It also caused the worst landslides in US history since 1927.
After the earthquake, some people said that they would never visit Yellowstone, because they were afraid they would be 7)________ in such a disaster caused by the earthquake. This is actually a foolish idea. Such a fear would 8)________ beautiful mountains for the rest of our lives. Even though earthquakes happen every day, such a powerful earthquake like the Yellowstone one does not happen frequently at all. We should feel 9)________ that very few of us will suffer such a bad natural disaster. Besides, if we know 10)________ and make careful preparations, the loss of lives could be avoided.