题目内容：
阅读下列短文,回答题目.Every year landslides(滑坡)cause 25 to 50 deaths and$1.5 billion in damage in the UnitedStates.They account for l5 percent of the deaths from natural disasters in Europe.And there wasevera singleeventkilled more than 200 people in the Philippines.Sending workers to stabilizemountainsides using steel bars and cement(水泥)Can help prevent disasters，but it introduces newdifficulties.Shaking drills produce harmful dust and loosen heavy，dangerous debris(岩屑).
“It’squite a risky job，”says Giorgio Pezzuto of D’Appolonia，an engineering company in Italy.
D’Appolonia，working with eight other companies，may have an answer：a three—ton robotcalled Roboclimber.“The idea is to operate a machine far away that Can drill without a human being on board，”says Pezzuto，the manager for the project，which is supported by the EuropeanCommigsion.Engineers claim that the machine will be faster and cheaper than manual labor.Therobot，a large radio—controlled four—legged mechanical spider，has cost at least$2 million sofar.
The final product should be able to climb unstable mountainsides，drill holes，insert bars and cement，and collect data on the stability.Testing should begin in May.
The underlined word“event”(Paragraph l)refers to__________. A．landslide
B．machine
C．earthquake
D．flood
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