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问题 单项选择题

已知钢筋的质量密度取7850kg/m3，公称直径为12mm的热轧光圆钢筋，其公称质量为( )。

A．0.617kg/m

B．0.888kg/m

C．0.943kg/m

D．1.21kg/m

答案

参考答案：B

问答题

ZAO Learnfast is a publisher of study materials for professional students. It entered into contracts with Anna and Yevgeni under which they would produce study texts, with each text to be divided into 12 chapters of approximately equal length.Shortly after beginning to write her study text, Anna discovered that the work was too demanding. She wrote to ZAO Learnfast explaining this, enclosing drafts of the three chapters she had managed to complete, together with her invoice for one-quarter of the fee.Three months after entering into the contract with Yevgeni, ZAO Learnfast was advised by the relevant professional body that the subject on which Yevgeni was writing his study text would be withdrawn within a year. ZAO Learnfast wrote to Yevgeni explaining that his study text would no longer be required. By this time, Yevgeni had written three chapters of the study text. ZAO Learnfast is prepared to pay Yevgeni one-quarter of the fee specified in the contract.The contracts between ZAO Learnfast and the two writers made no provision for these events.Required:

(a) Discuss the consequences of Anna’s withdrawal from her contract with ZAO Learnfast. (5 marks)
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单项选择题

各级公安机关和民警要善于从政治上考虑问题，判断形势，增强( )，在事关全局、事关政治方向、事关根本原则等重大问题上始终保持清醒和坚定。

A．政治敏锐性
B．政治鉴别力
C．政治敏锐性和政治鉴别力
D．政治警惕性
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