阅读理解
The ground we walk on seems firm, but deep under the earth and under the sea the rocks change and move. In some parts of the world there are “fire mountains”， which we call volcanoes. From time to time they burst open and throw out fire and burning ashes. These volcanoes are very dangerous.
Hong Kong does not have any volcanoes but there are many volcanoes in Indonesia and Philippines. There is also a famous mountain near Tokyo, Japan, which is a volcano too. Its name is Mount Fuji. For much of the year，it is covered with snow.
One of the most famous volcanoes which erupted in recent times was Krakatoa, on an island in Indonesia. The first explosions took place on 20th May, 1883, but the biggest eruption did not come until the 26th and 27th August of that year. The people on the island were used to the explosions by that time, and so they were completely unprepared for this terrible happening. Almost all the people on the island died and the explosion also made huge waves in the sea, which drowned (淹死) many people on the other island nearby. After the eruption was over，people saw that the whole northern part of the island had completely disappeared. Scientists say that 15 cubic (立方) kilometres of rocks and ash were thrown up in the explosion. The noise of the explosion was heard nearly 5,000 kilometres away in the middle of the Indian Ocean，and the city of Jakarta was completely dark for about two and a half hours.
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