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【单选题】
By the 1820's in the United States, when steamboats were common on western waters, these boats were mostly powered by engines built in the West (Pittsburgh, Cincinnati, or Louisville), and of a distinctive western design specially suited to western needs. The first steam engines 【21】______ practical use in England and the United States were 【22】______ low-pressure design. This was the type first 【23】______ by James Watt, then manufactured by the firm of Boulton and Watt. Steam was 【24】______ in a large, double-acting vertical cylinder, but the steam reached only a few pounds of pressure per square inch. It was low-pressure engines of this type that 【25】______ first introduced into the United States by Robert Fulton. He 【26】______ such a Boulton and Watt engine from England to run the Clermont. But this type of engine was ,expensive and complicated, 【27】______ many precision-fitted moving parts. The engine that became standard on western steamboats was of a different and 【28】______ design. It was the work primarily of an unsung hero of American industrial progress, Oliver Evans (1755-1819), the 【29】______ son of a Delaware farmer. Evans early became 【30】______ by the possibilities of mechanized production and steam power. As early as 1802 he 【31】______ a stationary steam engine of high-pressure design in his mill. Engines of this type were not 【32】______ , but before Evans they were generally considered 【33】______ and dangerous. Within a decade the high-pressure engine, the new type, had become standard on western waters. Critics 【34】______ of western conditions often attacked it as wasteful and dangerous. But people who really knew the Ohio, the Missouri, and the Mississippi 【35】______ , with good reasons, that it was the only engine for them. In 【36】______ western rivers the weight of vessel and engine 【37】______ important a heavy engine added to the problem of navigation. The high-pressure engine was 【38】______ lighter in proportion to horsepower, and, with less than half as many moving parts, was much easier and cheaper to repair. The main advantages of low-pressure engines were safe operation and 【39】______ of fuel consumption, 【40】______ of which meant much in the West.. 【21】
A.
on
B.
by
C.
for
D.
in
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【判断题】车削的特点是刀具沿着所要形成的工件表面,以一定的背吃刀量、进给量和切削速度对回转的工件进行切削。
A.
正确
B.
错误
【判断题】一维对象指针数组的每个元素应该是某个类的对象的地址值
A.
正确
B.
错误
【多选题】2018年1 月,中央一号文件对实施乡村振兴战略提出指导意见,并提出把实现乡村振兴作为全党的共同意志、共同行动,做到认识统一、步调一致,( ),加快补齐农业农村短板。
A.
在干部配备上优先考虑。
B.
在要素配置上优先满足。
C.
在资金投入上优先保障。
D.
在公共服务上优先安排。
【单选题】车削加工的特点是刀具沿着所要形成的工件表面,对()进行切削。
A.
运动的工件
B.
静止的工件
C.
回转的工件
D.
移动的工件
【简答题】时代新人要以 为己任。
【单选题】时代新人要以( )为己任
A.
人民幸福
B.
民族复兴
C.
个人发展
【单选题】下列会计报表中,反映企业在某一特定日期财务状况的是( )。
A.
利润表
B.
利润分配表
C.
资产负债表
D.
现金流量表
【单选题】2018年中央一号文件中提到,把实现乡村振兴作为全党的共同意志、共同行动,做到认识统一、步调一致,在( )上优先考虑,在( )上优先满足,在( )上优先保障,在公共服务上优先安排,加快补齐农业农村短板。
A.
政策方针、资金保障、生活投入
B.
领导配置、组织分配、资金投入
C.
干部配备、要素配置、资金投入
D.
指导意见、创新发展、资金投入
【单选题】车削特点是刀具沿着所要形成的工件表面,以一定的背吃刀量和()对回转工件进行切削
A.
切削速度
B.
进给量
C.
运动
D.
方向
【单选题】车削特点是刀具沿着所要形成的工件表面,以一定的( )和进给量对回转工件进行切削
A.
切削速度
B.
运动
C.
背吃刀量
D.
方向
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