读图我国三个“地带的产业结构图”，如果图例代表三个产业，那么，正确的组合是（）

如图所示，平行金属导轨与水平面成θ角，导轨与固定电阻R₁和R₂相连，匀强磁场垂直穿过导轨平面。有一导体棒ab，质量为m，导体棒的电阻与固定电阻R₁和R₂的阻值均相等，与导轨之间的动摩擦因数为μ，导体棒ab沿导轨向上滑动，当上滑的速度为V时，受到安培力的大小为F。此时

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A．电阻R₁消耗的热功率为Fv／3

B．电阻R₁消耗的热功率为Fv／6

C．整个装置因摩擦而消耗的热功率为μmgvcosθ

D．整个装置消耗的机械功率为（F＋μmgcosθ）v

动词填空（本大题共10分，每小题1分）

A year ______________ (divide) into 52 weeks.

The maths problem is not easy enough for each of us ______________ (work) out.

When I got to the station, my friends ___________ (wait) for me.

It’s silly of you ___________ (not forgive) others for their mistakes.

Most boy school students have their hair __________(cut) once a month.

I would rather sell the old house _____(buy) a new one.

You should be confident enough _________ (take) this job. You’re the most suitable person.

The pupils are having fun      __  (make)cassettes..

Some day the scientist ____________ (clone) every living thing.

10. They_________(treat) well when they became sick.

生产力的发展、私有制的产生，是警察产生的经济条件。( )

试述格构柱对虚轴的整体稳定性计算为什么要用换算长细比？

随着信息和信息技术发展起来的现代密码技术，不仅被用于解决信息的保密性，而且也用于解决信息的（）。

A、完整性

B、可用性

C、可信性

D、透明性

E、可控性