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Eruptions of Mount Saint Helens
On March 27，the US Govemment scientists made a decision after they predicted the emption of Mount Saint Helens．They telephoned all state and local officials in the area and told them that a serious eruption was possible at any time,Roads were closed to every one except scientists and forest keepers struggled to keep curious visitors away from the mountain.
Shortly after noon on March 27，Mount Saint Helens erupted for the first time in 1 23 years．People living north of the mountain heard a loud boom that shook their windows，and airline pilots flying near the volcano soon afterwards described a thick black colunm of ash and steam shooting more than 2，100 meters into the sky．
Later,scientists found that the explosion had made a new crater(大坑)in the top of the mountain．not far from the old crater．The north side of the peak now had a huge bulge(凸出部分) where rock and ice had been pushed out by the eruption．
A second eruption shook the mountain on March 28．It，too，sent up a column of black ash high into the sky．By March 29，scientists flying over the mountain saw that a second crater
formed about 9 meters from the first one．Strange blue flames flickered(闪烁)inside the crater and sometimes jumped from one crater to the other．
By April the mountain had erupted several more times and the snow on the north slope of the peak was black with ash．Ash carried by the wind had fallen on towns as far as 240 kilometers
away from Mount Saint Helens．
During the first week of April，Mount Saint Helens gave scientists something new to worry about：harmonic tremors(震动)recorded by scientists showed a big eruption would happen．All during April and into May Mount Saint Helens continued to shudder(震动)and shoot out ash．By.April8, two craters had merged to from a vast hole nearly a half of a kilometer wide and 250 meters deep．
Scientists'main worry during this time was the growing bulge of rock and ice on．the north face of the mountain．By May 7 scientists feared the worst．Their warnings led Washington Governor to set up safety zones around the mounmin．The inner"red"zone was open to scientists only．The outer"blue"zone was open only to people who got special permits．But in spite of
these warnings，some people got past the road barriers and risked their lives trying to get close to the volcano．
16 American scientists predicted that Mount Saint Helens was to erupt soon.
A Right B Wrong C Not mentioned
17 Pilots flying at the height of more than 2，100 meters saw a thick black column of ash and steam shooting up into the air from the crater．
A Right B Wrong C Not mentioned
18 A new crater,which was to the south of the old one，was formed after the Second eruption.
A Right． B Wrong C Not mentioned
19 The quakes recorded during the first week of April in the area of Mount Saint Helens warned scientists of a new eruption．
A Right B Wrong C Not mentioned
20 Two scientists lost their lives during the second eruption of Mount Saint Helens.
A．Right B Wrong C Not mentioned．
2 1 Most of the dreadful eruptions of Mount Saint Helens took place in early May．
A Right B Wrong C Not mentioned
22 The eruption of Mount Saint Helens attracted a large number of foreign tourists．
A Right B Wrong C Not mentioned