题目

Now if you’ve got nothing to do today, why not go to the east part of the city and get digging? That’s the message from No.1 Senior High School,  ___34._____ is organizing a tree planting event near East Mountain. In order to improve the environmental __35.____ (educate) of its students and get more people __36._ (organize), the school is planning to plant __37.__ total of 1,400 trees paid by the government over the next few days. They are hoping to plant half of them today and they are looking __38.__ volunteers to come along and help. No experience is necessary, __39.__现在给出下列四种振动:A.共振              B.无阻尼振动        C.阻尼振动          D.受迫振动(1)荡秋千时,秋千的振动属于________________________.(2)受迫振动中,策动力的频率等于固有频率的现象称为________________________.(3)音叉长时间的振动,应该看作是________________________.(4)忽略阻力时,浮在水面上的木块上下振动,可看作________________________.
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