关于力和运动状态的改变,下列说法不正确的是() A.物体加速度为零,则运动状态不变

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问题:

关于力和运动状态的改变,下列说法不正确的是()

A.物体加速度为零,则运动状态不变

B.只要速度大小和方向二者中有一个发生变化,或者二者都变化,都叫运动状态发生变化

C.物体运动状态发生改变就一定受到力的作用

D.物体运动状态的改变就是指物体的加速度在改变

考点:高中物理牛顿第一定律牛顿第一定律题库
题型:单项选择题

结合上皮的附着方式是()

A.获得性膜与桥粒结构

B.桥粒结构

C.缝隙连接

D.直接附着

E.半桥粒与基板

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Opinion polls are now beginning to show that, whoever is to blame and whatever happens from now on, high unemployment is probably here to stay. This means we shall have to find ways of sharing the available employment more widely.
But we need to go further. We must ask some fundamental questions about the future work. Should we continue to treat employment as the norm Should we not rather encourage many ways for self-respecting people to work Should we not create conditions in which many of us can work for ourselves, rather than for an employer Should we not aim to revive the household and the neighborhood, as well as the factory and the office, as centers of production and work
The industrial age has been the only period of human history in which most people’s work has taken the form of jobs. The industrial age may now be coming to an end, and some of the changes in work patterns which it brought may have to be reversed. This seems a daunting thought. But, in fact, it could offer the prospect of a better future for work. Universal employment, as its history shows, has not meant economic freedom.
Employment became widespread when the enclosures of the 17th and 18th centuries made many people dependent on paid work by depriving them of the use of the land, and thus of the means to provide a living for themselves. Then the factory system destroyed the cottage industries and removed work from people’s homes. Later, as transport improved first by rail and then by road, people commuted longer distances to their places of employment until, eventually, many people’s work lost all connection with their home lives and the places in which they live.
Meanwhile, employment put women at a disadvantage. In preindustrial times, men and women had shared the productive work of the household and village community. Now it became customary for the husband to go out to paid employment, leaving the unpaid work of the home and families to his wife. Tax and benefit regulations still assume this norm today, and restrict more flexible sharing of work roles between the sexes.
It was not only women whose work status suffered. As employment became the dominant form of work,young people and old people were excluded—a problem now,as more teenagers become frustrated at school and more retired people want to live active lives.
All this may now have to change.
The time has certainly come to switch some effort and resources away from the idealist goal crea- ting jobs for all, to the urgent practical task of helping many people to manage without full-time jobs.

What is the main idea of the passage

A. Employment became widespread in the 17th and 18th centuries.
B. Unemployment will remain a major problem for industrialized nations.
C. The industrial age may now be coming to an end.
D. Some efforts and resources should be devoted to helping more people cope with the problem of unemployment.

题型:单项选择题

结构化设计方法(SD) 与结构化分析方法(SA) 一样,遵循______模型,采用逐步求精技术,SD方法通常与SA相联,即依据数据流图设计程序的结构。

A.实体模型

B.原型

C.抽象思维

D.生命期

题型:单项选择题

堤顶的平整还要体现在横向坡度的饱满上,堤顶应保持向()倾斜。

A.一侧或两侧

B.临河

C.背河

D.上游

题型:单项选择题

当滚动轴承采用浸油润滑时,油面高度()超过轴承最下面滚动体的中心线。

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