（ ）是指在一次平均数之外，所有先进数值的二次平均数。[2008年11月四级真题] 发布时间：2017-06-25 17:00 │ 来源：www.tikuol.com 题型：单项选择题 问题： （ ）是指在一次平均数之外，所有先进数值的二次平均数。[2008年11月四级真题]A．平均日产量 B．简单平均值 C．先进平均工时 D．加权平均值
题型：单项选择题 用所给动词的适式填空.eat want get exercise make start help listen take have 1. ___________every day is good for your health.2. We should try __________ more fruit and vegetables.3. Let's____________ our new lesson.4. She ____________ to improve her English.5. Fruit ____________us to keep in good health.6.The trees are too high. We can't ____________the apples on them.7. Does it ___________a big difference if you eat a lot of vegetables every day?8. Our teacher wants us ___________to her carefully in class.9. My sister ____________ the No. 1 bus to work.10. Do you ____________a healthy life style if you exercise every day? 查看答案
题型：单项选择题 如图所示，AB是一质量为m的均匀细直杆，A端靠在光滑的竖直墙壁上，B端置于水平地面上，杆身与竖直方向夹角为θ，杆与地面的摩擦系数为μ，保持平衡，则此时杆与地面的摩擦力为（ ）A．mgtgθB．mgsinθC．μmgD．μmg 查看答案
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