暗配管宜沿最近的路线敷设并应减少弯曲，埋入墙或混凝土内的管子_爱下问搜题

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问题单项选择题

暗配管宜沿最近的路线敷设并应减少弯曲，埋入墙或混凝土内的管子离表面的净距不得小于( )mm。

A．10
B．15
C．20
D．25

答案

参考答案：B

完形填空

Mr Smith from London. Now he is in China. He is .He teaches English a middle school. He works very hard. His students like very much. He can a little Chinese . His students often teach him Chinese Sundays. Mr Smith likes playing football . He often plays football his students.
　　Mr Smith a son. His name is Jack. He is student. He studies in a middle school. He goes to school bike everyday. He gets back home at four in the afternoon. He likes TV in the evening.

问答题

设f(x)在区间[a，b]上连续，在(a，b)内可导，f’(x)＞0，[*]存在。证明：
(Ⅰ) 在(a，b)内有f(x)＞0；
(Ⅱ) 存在ξ∈r(a，b)，使得[*]
(Ⅲ) 存在η∈(a，b)，使得[*]