San Francisco is a big city which lies in the west of the United States very near the Pacific, where two earth's plates often meet and jump. So earthquake is a  1   word to hear there. It is recorded that at least 2 big earthquakes have happened in San Francisco since the beginning of the   3 century. One happened in 1906, the other in 1989.

The second worst earthquake 4 San Francisco on the evening of October 17, 1989, when people were travelling to their   5 . A wide and busy overhead road fell onto the one 6 Many people were killed in their cars. A few   7   ones were not hurt, but many thousands became   8    A large number of weak buildings didn't   9 in the quake and the   10 electricity was cut off for several days, too.

Nobody but scientists can explain the   11   of earthquakes. In their opinion, although earthquake cannot be   12 . we can do things to make sure they do not destroy whole cities. They suggest we should not build houses along the   13   where earth's plates join together. We should build houses   14   instead of on sand. And the buildings have to be as   15   as possible. Scientists are also studying earthquakes, which may someday help to save hundreds of lives.                                                

        KEY: 1. C  2. A   3. D   4. A  5. B  6. C  7. D  8. A  9. C  10. D  11. B 12. A  13. D  14. B   15. A