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【单选题】
胶印机机械运动的冲力除印刷压力外,主要来自()。
A.
滚筒离让
B.
水、墨辊传动
C.
递纸装置的往复
D.
递纸牙往复摆动和滚筒叼牙开闭
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参考答案：
参考解析：
刷刷题刷刷变学霸
举一反三
【单选题】第二篇 Pushbike Peril Low speed bicycle crashes can badly injure—or even kill—children if they fall onto the ends of the handlebars (车把). So a team of engineers is redesigning the humble h...
A.
it is not easy to persuade manufacturers to adopt the new design.
B.
the team of engineers has not found any countermeasures.
C.
children like to ride bicycles at a very low speed.
D.
a lot of children were killed in bicycle accidents in the past 30 years.
【单选题】(2005年)要用冲床在厚度为t的钢板上冲出一圆孔，则冲力大小( )。
A.
与圆孔直径的平方成正比
B.
与圆孔直径的平方根成正比
C.
与圆孔直径成正比
D.
与圆孔直径的三次方成正比
【单选题】要用冲床在厚度为t的钢板上冲出一圆孔，则冲力大小 ( )。
A.
与圆孔直径的平方成正比
B.
与圆孔直径的平方根成正比
C.
与圆孔直径成正比
D.
与圆孔直径的三次方成正比
【多选题】下列情况属于机械运动的是哪几项?( )
A.
北京到上海的高铁列车在高速行驶
B.
中国的综合国力在飞速发展
C.
刘翔在奥运会110米跨栏决赛中
D.
煤炭正在熊熊燃烧
【单选题】Pushbike Danger Low speed bicycle crashes can badly injure—or even kill—children if they fall onto the ends of the handlebars (车把). So a team of engineers is redesigning it to make it safer. Kristy A...
A.
Thirty.
B.
Ninety.
C.
50 percent.
D.
More than a third.