Câu hỏi:

Read the following passage and mark the letter A, B, C, or D on your answer sheet to choose the word or phrase that best fits each of the numbered blanks from 25 to 29 

     An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. At the Earth's surface, earthquakes are recognized (25) _______ vibration, shaking and sometimes displacement of the ground. The vibrations may vary in (26) _______. They are caused mostly by slippage within geological faults, but also by other events such as volcanic activity, landslides, mine blasts, and nuclear tests. The underground point of (27) _____ of the earthquake is called the focus. The point directly above the focus on the surface is called the epicenter. Earthquakes by themselves rarely kill people or wildlife. It is usually the secondary events (28) _______ they trigger, such as building collapse, fires, tsunamis (seismic sea waves) and volcanoes, that are actually the human disaster. Many of these could possibly be avoided by better construction, safety systems, early warning and (29) _______ planning.