Some countries have large numbers of earthquakes. Japan is one of them. Others do not have

many; for example, there are few earthquakes in Britain.

There is often a great noise during an earthquake. The earth shakes. Houses fall down. Railway lines are broken. Sometimes many people are killed in an earthquake.

Earthquakes often happen near volcanoes, but this is not always true. The centers of some are under the sea. The bottom of the sea suddenly moves. The powerful forces inside the earth break the rocks. The coast is shaken and great waves appear. These waves travel long distances and rush over the land when they reach it. (42) They are strong enough to break down houses and other buildings; sometimes they break more buildings than the earthquake itself.

What kind of buildings stands up best in an earthquake？ A building with concrete walls is perhaps the best. A steel frame. will make it even stronger. The frame. holds the different parts together, and the walls do not easily fall. There is less chance of fire because concrete and steel do not burn. This kind of building is the safest.

Which of the following shows that an earthquake happens？

A．The earth and the buildings shake badly.

B．There is a great noise in the sky.

C．The sky is covered with thick clouds.

D．The tigers and lions in the zoo run about nervously.