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问题 选择题

一个自由电子沿电场线方向射入如图所示，它在电场中的运动情况是（　　）

A．速度减小，加速度增大

B．速度增大加速度减小

C．速度和加速度都减小

D．速度和加速度都增大

答案

电子带负电，所受电场力方向与电场线方向相反，水平向左．电子的速度方向水平向右，所以电子的速度减小．而电场线越来越密，场强越来越大，电子的加速度越来越大．

故选A

单项选择题

Cody Scott would like to screen potential equity investments to identify value stocks and selects firms that have low price-to-sales ratios. Unfortunately, screening stocks based only on this criterion may result in stocks that have poor profitability or high financial leverage, which are undesirable to Scott. Which of the following filters could be added to the stock screen to best control for poor profitability and high financial leverage Filter 1—Include only stocks with a debt-to-equity ratio that is above a certain benchmark value. Filter 2—Include only dividend paying stocks. Filter 3—Include only stocks with an assets-to-equity ratio that is below a certain benchmark value. Filter 4—Include only stocks with a positive return-on-equity.Poor profitability High financial leverage（）①A. Filter 2 Filter 3 ②B. Filter 2 Filter 1 ③C. Filter 4 Filter 3

A. ①

B. ②

C. ③
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问答题

基本不等式”是高中数学教学中的重要内容，请完成下列任务：

在“基本不等式”起始课的“教学重点”设计中，有两种方案： ①强调基本不等式在求数值中的应用，将基本不等式的应用作为重点。 ②强调基本不等式的背景，过程与意义，将学生感受和体验“基本不等式”中“基本”的意义作为教学重点。 你赞同哪种方案？简述理由。
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