有关先天性肾盂输尿管交界处梗阻的原因，下列哪项是错误的（） A.先天性狭窄 B.异位

简述“经济人”假设与“社会人”假设在管理策略上有何区别

（）不是矩阵式物流组织结构优点。

A.物流部门作为责任中心，可以基于目标进行管理

B.组织结构比较灵活，适合各种不同类型企业

C.允许物流经理对物流进行一体化的规划和设计，可以提高物流的整合效益

D.物流部门既负责整体物流的规划和设计，又负责物流业务的日常运作，职权清晰，物流效率较高

如图所示，光滑的平行金属导轨CD与EF间距为L=1 m，与水平夹角为θ=30°，导轨上端用导线CE连接（导轨和连接线电阻不计），导轨处在磁感应强度为B=0.1 T、方向垂直于导轨平面向上的匀强磁场中。一根电阻为R=1 Ω的金属棒MN两端有导电小轮搁在两导轨上，棒上有吸水装置P。取沿导轨向下为x轴正方向，坐标原点在CE中点。开始时棒处在x=0位置（即与CE重合），棒的起始质量不计。当棒自静止起下滑时，便开始吸水，质量逐渐增大，设棒质量的增大与位移x的平方根成正比，即，k为一常数，。

(1)猜测金属棒下滑过程中做的是什么性质的运动，并加以证明；

(2)求金属棒下滑2m位移时速度为多大？

Some politicians are scurrying about with much zest and anticipation. It’s time, their polls inform them, to find the quick fix for what they have determined is a society plagued by the irregular heartbeat of deficient values.

But there are contradictions that intrude on this denunciatory atmosphere. If there are moral omissions in the society, they cannot be sealed by instant, slenderly based attacks on entertainment. The plain fain fact is we are rearranging our priorities in the wrong way.

We are today misplacing our energies and our funding by directing all sorts of incentives to high schools and colleges. Too late. The moral scaffolding has been built by then, for better or worse. How then to begin this revision of life conduct We must introduce in pre-school, and keep alive through grade five, a new school course.

The course could be titled, "What is right, and what is plainly wrong. " For 30 minutes each day, the teacher would illuminate for these very young children what William Faulkner labeled "the old verities", the words that construct and implement the daily moral grind in every durable society must engage if it is to be judged a "just" society.

These are words like duty, honor, service, integrity, pity, pride, compassion and sacrifice, plus the clear admonition that violence is wrong. To the teaching of the meaning of those words must be added that cleansing rule of treating other people as you would want them to treat you. And most of all to make sure that these kids understand with growing clarity that home, school and church are the sanctuaries for their later life.

There is a grand simplicity to this kind of school course. It enters a child’s mind early, burrowing deep into those recesses of the human brain that even today advanced medical science has not been able to penetrate.

If you ask enough people, you will find that most of us remember our first-or second-grade teacher. I remember Miss Corbett and Miss Walker, who read to us before we really understood, but the words had weight and allure. We listened and, without really knowing it, we learned and saved what we learned. Perhaps it was because what we heard in those early school years was the first entry into our learning vessel.

Absent this kind of early instruction, absent the building of this moral shield, no congressional law, no presidential executive order, no fiery rhetoric will salvage a child’s conduct nor locate a missing moral core.

With respect to the rectification of the situation the author believes that().

A. it’s easy to carry moral education at and above high school level

B. high school students don’t need any further moral education

C. no return is to be gained on the investment in moral education

D. moral education in primary school or still earlier should be much emphasized