B．zones with a high probability of earthquakes

　　C．breaks between two sections of the earth's surface

　　D．the two layers of earth along a fault

　　解析：选B　细节理解题。根据第一段的第三句可知，地震多发地带被称为earthquake belts。

　　2．The San Andreas fault is .

　　A．an active fault system

　　B．a place where earthquakes have been predicted correctly

　　C．a place where earthquakes have been controlled

　　D．at the foot of the Rocky Mountain

　　解析：选A　细节理解题。根据第二段可知，该地区为地震比较活跃的地区。

　　3．What did scientists learn about earthquakes at the Rocky Mountain Arsenal?

　　A．They occur at about 4,000 metres below ground level.

　　B．The injection of water into earthquake faults prevents earthquakes from occurring.

　　C．They are usually caused by the oil in the faults.

　　D．Harmful earthquakes could be prevented by causing harmless earthquakes.

　　解析：选D　细节理解题。根据最后一段尾句可知。

　　4．What can be said about the experiments at the Rocky Mountain Arsenal?

　　A．They have no practical value in earthquake prevention.

　　B．They may have practical value in earthquake prevention.

　　C．They are certain to have practical value in earthquake prevention.

　　D．Nothing is told about their practical value in earthquake prevention.

　　解析：选B　推理判断题。根据科学家的试验，通过向断裂带注水可以引发小地震，从而使地震的能量得到释放，因此也就降低了大地震爆发的可能。

　　B

　　There are over 500 known active volcanoes in the world and thousands of extinct volcanoes. Volcanoes are found on every continent except Australia. There are about 80 active volcanoes under the oceans. Volcanoes are both terrifying and fascinating. In order to understand why volcanic eruptions happen, it is necessary to know some things about how the Earth is made.

　　The part of the Earth we live on is an 18­mile­thick layer of solid rock called the crust. Beneath the crust is a layer called the mantle (地幔), it is hot enough to melt some of the rock, creating magma (岩浆).

When the magma finds cracks in the Earth's crust, it rises up. Gas bubbles (气泡) inside the magma grow bigger and try to escape as the molten rock gets closer to the Earth's surface. When the gas bubbles can't be held back any longer, the volcano erupts. Imagine shaking a soda