定性的工作分析方法是（）A.职位分析问卷法 B.功能性工作分析 C.职位评级 D.关

在极坐标系（ρ，θ）（0≤θ＜2π）中，曲线ρ（cosθ+sinθ）=1与ρ（sinθ-cosθ）=1的交点的极坐标为______．

如图所示，小木块在沿斜面向上的恒定外力F作用下，从A点由静止开始作匀加速运动，前进了0.45m抵达B点时，立即撤去外力．此后小木块又前进0.15m到达C点，速度为零．已知木块与斜面动摩擦因数μ=

3

3

/6，木块质量m=1kg．求：

（1）木块向上经过B点时速度为多大？

（2）木块在AB段所受的外力多大？（ g=10m/s²）

I am Steve. I was born and grew up in South Wales. My favorite place to play was out on the hills where my imagination had plenty of space to expand.
My family moved out of Wales when I was thirteen. I went to a new school. One of my subjects was French. Because I had never learned any French, my teacher told me to sit in the corner and write anything I was interested in. That’s the time I started writing, just for myself, and I’ve been writing ever since.
I have always loved BIG IDEAS, and so I enjoy writing fantastic stories. And I also write horror stories. I think they are like the old fairy tales, and can teach you important things.
I am in my forties on the outside, twelve on the inside. I like rock music, Indian and Chinese food, and I enjoy drinking. I live in a small village with my wife Mary, ducks, cats, oats, hens and lots of rabbits. If you’d like to find out more about me and hope to buy my books, go to www.sbowkett.freeserve.co.uk.

According to the passage, the writer keeps ______.

A．cats, hens and pigs
B．ducks, goats and rabbits
C．hens, rabbits and dogs
D．rabbits, pigs and cats

启运蒸汽往复泵时应（）

A、先开入出口阀后开泵

B、先开泵后开入出口阀

C、没关系

D、以上均错误

在其他能源中，核能具有能量密度大，地区适应性强的优势．在核电站中，核反应堆释放的核能被转化为电能．核反应堆的工作原理是利用中子轰击重核发生裂变反应，释放出大量核能．

（1）核反应方程式

23592

U+n→

14156

Ba+

9236

Kr+aX是反应堆中发生的许多核反应中的一种，n 为中子，X为待求粒子，a为X的个数，则X为______，a=______．以m_U、m_Ba、mkr分别表示

23592

U、

14156

Ba、

9236

Kr核的质量，m_n、m_p分别表示中子、质子的质量，c为光在真空中传播的速度，则在上述核反应过程中放出的核能△E=______．

（2）有一座发电能力为P=1.00×10⁶kW的核电站，核能转化为电能的效率η=40%．假定反应堆中发生的裂变反应全是本题（1）中的核反应，已知每次核反应过程放出的核能△E=2.78×10^-11J，

23592

U核的质量mU=390×10-27kg．求每年（1年=3.15×10⁷s）消耗的

23592

U的质量．