一梯形断面的明渠，水力半径R=0.8m，底坡i=0.0006，粗糙系数n=0.025_爱下问搜题

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问题单项选择题

一梯形断面的明渠，水力半径R=0.8m，底坡i=0.0006，粗糙系数n=0.025，作均匀流时该渠的断面平均流速为：（）

A.0.96m/s

B.1.0m/s

C.0.84m/s

D.1.2m/s

答案

参考答案：C

解答题

已知函数f（x）=-

x³+x²+b，g（x）=

，其中x∈R
（I）当b=

时，若函数F(x)=

为R上的连续函数，求F（x）的单调区间；
（Ⅱ）当a=-1时，若对任意x₁，x₂∈[1，2]，不等式g（x₁）＜f（x₂）恒成立，求实数b的取值范围．

补全对话，情景问答

选择正确的单词填空完成对话。

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Tom: How are you?
Jack: Fine, thank you. It is ____________ today. It's five degrees below zero.
Tom: Look! it's ____________ now.
Jack: We don't go to ____________ today. Let's ____________ together.
Tom: OK. What do you like to do?
Jack: I like to ____________ on the snow.
Tom: I can ____________ on the ice, but I can't do that! I want to ____________.
Jack: OK! I will ____________ you.