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听力原文: It was an Italian inventor who created the first wireless device for sending out radio signals in 1895. But not until the American inventor Lee De Forest built the first amplifying vacuum tube in 1906 did we get the first radio as we know it. And the first actual radio broadcast was made on Christmas Eve of 1906. That's when someone working from an experimental station in Brand Rock, Massachusetts, arranged the program of two short musical selections, a poem and a brief holiday greeting. The broadcast was heard by wireless operators on ships with a radio through several hundred miles. The following year, De Forest began regular radio broadcasts in New York. These programs were similar to much of what we hear on the radio today in that De Forest played only music. But because there were still no home radio receivers, De Forest's audience consisted of only wireless operators on ships in New York harbor. There is no doubt that radio broadcasting was quite a novelty in those days. But it took a while to catch on commercially. Why? For the simple fact that only a few people, in fact, only those who tinkered with wireless telegraphs as a hobby, owned receivers. It wasn't until the 1920's that someone envisioned mass appeal for radio. This was radio pioneer, David Sarnoff, who predicted that one day there would be a radio receiver in every home. When was the first actual radio broadcast made?
A.
On Christmas Eve of 1906.
B.
On Christmas Eve of 1960.
C.
On Christmas Eve of 1895.
D.
On Christmas Eve of 1859.
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【单选题】下列属于钾肥的是(  )
A.
NH 4 Cl
B.
K 2 CO 3
C.
NH 4 H 2 PO 4
D.
Ca 3 (PO 4 ) 2
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A.
极薄片
B.
薄片
C.
直片
D.
厚片
E.
宽丝片
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A.
正确
B.
错误
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A.
银行审贷贷款申请签订合同发放贷款贷款结清按期还款
B.
签订合同银行审贷贷款申请发放贷款按期还款贷款结清
C.
贷款申请银行审贷签订合同发放贷款按期还款贷款结清
D.
签订合同银行审贷贷款申请发放贷款按期还款贷款结清
【单选题】工程上常用( )指标控制回填土的质量。
A.
土的含水量
B.
土的干密度
C.
土的孔隙率
D.
土的饱和度
【简答题】简述离合器的动力传递路线和分离过程。
【单选题】木质类、动物角质类药材宜切( )
A.
极薄片
B.
薄片
C.
厚片
D.
直片
E.
段片
【简答题】将下列代码转换成十进制数: (1) ( 001101010010 ) 8421BCD = 。 (2) ( 101110010100 ) 5421BCD =
【单选题】本门课程操作成绩占总成绩百分比为
A.
10%
B.
20%
C.
30%
D.
40%
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