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问题 问答题 简答题

高速铁路用轨的性能特点是什么？（（答出三个即可））

答案

参考答案：（1）具有高耐磨性、高强度（2）良好的抗疲劳性能。（3）良好的焊接性能；（4）良好的抗断裂性能；（5）高的平直度和尺寸精度。

单项选择题

等产量曲线是指在这条曲线上的各点代表( )。

A．为生产同产量投入要素的各种组合比例是不能变化的

B．为生产同等产量投入要素的价格是不变的

C．不管投入要素量如何，产量总是相等的

D．投入要素的各种组合所能生产的产量都是相等的
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单项选择题

Most computer systems are (71) to two different groups of attacks：insider attacks and outsider attacks．A system that is known to be (72) to an outsider attack by preventing (73) from outside can still be vulnerable to the insider attacks accomplished by abusive usage of (74) users．Detecting such abusive usage as well as attacks by outsides not only provides information on damage assessment,but also helps to prevent future attacks．These attacks are usually (75) by tools referred to as Intrusion Detection Systems．

（74）处填（）。

A．power

B．rights

C．authorized

D．common
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