Why do earthquakes happen? Scientists explain that the outside of the earth is made of a number of different plates(极块). For example, at San Francisco the Pacific（太平洋的） Plate which is moving towards the northwest meets the North American Plate. The Pacific Plate is moving very  slowly-at 5. 3 centimetres a year. Sometimes these two plates stop and do not move for years. Then suddenly, they jump and an earthquake is felt. As the movement of these plates, West America near the sea has always been a bad place for earthquakes. When the 1906 earthquake happened, the Pacific Plate jumped 5-6 metres to the north.
We cannot stop earthquakes, but we can do things to make sure they don't destroy(毁坏) the whole of cities. First ,it is not a good idea to build houses along the lines, where two of the earth's plates join together. Second, if you think there may be an earthquake, it is better to build houses on rock not on sand. Third, you must make the houses as strong as possible. Weak buildings will fall down in an earthquake, but strong ones may stay up.
Scientists explain that _____.

A．the outside of the earth is made of a plate

B．the inside of the earth is made of different plates

C．the outside of the earth is made of lots of different plates

D．the earth is a plate

An earthquake can be felt ______

A．when two plates push each other

B．when one plate pulls another plate

C．when one plate jumps over another plate

D．when two plates don't move

An earthquake shook San Francisco in the past because _____.

A．San Francisco stands along between the Pacific Plate and the North American Plate

B．San Francisco stands near the Pacific

C．San Francisco is near the sea

D．the city of San Francisco wasn't built very well

We can't stop _____.

A．earthquakes from destroying the whole of cities

B．earthquakes

C．building houses along the earthquake line

D．building weak houses at San Francisco

We _____to make sure earthquakes don't destroy the whole of cities.

A．should build houses far from the earthquake line

B．should build houses on rock not on sand if we think there may be an earthquake

C．must make the houses as strong as possible

D．A, B and C