问题 问答题

[附加题]如图所示,一半径为R的绝缘圆形轨道竖直放置,圆轨道最低点与一条水平轨道相连,轨道都是光滑的.轨道所在空间存在水平向右的匀强电场,场强为E.从水平轨道上的A点由静止释放一质量为m、带正电为q的小球,为使小球刚好能到达圆环最高点;求释放点A距圆轨道最低点B的距离s.

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答案
阅读理解

One evening in February 2007 . a student named Paula Ceely brought her car to a stop on a remote in Wales . She got out to open a metal gate that blocked her path . That's when she heard the whistle sounded by the driver of a train.Her Renault Clio parked across a railway line. Second later,she watched  the train drag her car almost a kilometre down the railway tracks.

Ceely's near miss  made the news because she blamed it on her GPS device(导航仪).She had never driven the route before .It was dark and raining heavily . Ceely was relying on her GPS. But it made no mention of the crossing ."I put my complete trust in the device and it led me right into the path of a speeding train ,"she told the BBC.

W ho is to blame here ? Rick Stevenson ,who tells Ceely's story in his book When Machines Fail US, finger at the limitations of technology. We put our faith in digital devices, he says,

but our digital helpers are too often not up to the job. They are filled with small  problems. And it’s not just GPS devices: Stevenson takes us on a tour of digital disasters involving everything from mobile phones to wireless key boards.

The problem with his argument in the book is that it’s  not clear why he only focuses digital technology,while  there may be a number of other possible  causes. A map-maker might have left the crossing off a paper map. Maybe we should blame Ceely for not paying attention. perhaps the railway authorities are at fault for poor signaling system. Or maybe someone has studied the relative dangers and worked out that there really is something specific wrong with the CPS equipment. But Stevenson doesn’t say.

It’s a problem that runs through the book. In a section on cars, Stevenson gives an accout of the advanced techniques that criminals use to defeat computer-based locking systems for cars. He offers two independent sets of figures on car theft; both show a small rise in some parts of the country. He says that once once again not all new locks have proved reliable. Perhaps, but maybe it’s also due to the shortage of policemen on the streets. Or changing social circumstances. Or some combination of these factors .

The game between humans and their smart devices  is complex. It is shaped by economics and psychology and the cultures we live in. Somewhere in the mix of those forces there may be  way a wiser use of technology.

If there is such a way, it should involve more than just  an awareness of the shortcomings of our machines. After all, we have lived with them for thousands  of years. They have probably been fooling us for just as long .

小题1:What did Paula Ceely think was the cause of her accident?           

A.Shewasnotfamiliarwiththeroad.

B.Itwasdarkandrainingheavilythen.

C.The railway works failed to give the signal.

D.Her GPS device didn’t tell her about the crossing小题2:The phrase”near miss” (paragraph 2 ) can best be replaced by _______.

A.closebit

B.heavyloss

C.narrow escape

D.bigmistake小题3:Which of the following would Rick Stevenson most probably agree with?          

A.Moderntechnologyiswhatwe can’tlivewithout.

B.Digitaltechnologyoftenfalls shortofoutexpectation.

C.Digitaldevicesaremore reliablethantheyusedtobe.

D.GPSerrorisnottheonly causeforCelery’saccident.小题4:

In the writer’s opinion, Stevenson’s argument is________.

A.one-sided

B.reasonable

C.puzzling

D.well-based小题5:

What is the real concern of the writer of this article?

A.The major causes of traffic accidents and car thefts.

B.The relationship between humans and technology

C.Theshortcomingsofdigital devicesweuse.

D.Thehuman unawarenessoftechnicalproblems.

问答题

已知数据文件IN60.DAT中存有200个4位数,并已调用读函数readDat()把这些数存入数组a中,请编制一函数JsVal(),其功能是:把千位数字和十位数字重新组合成一个新的十位数ab(新十位数的十位数字是原4位数的千位数字,新十位数的个位数字是原4位数的十位数字),以及把个位数和百位数组成另一个新的十位数cd(新十位数的十位数字是原4位数的个位数字,新十位数的个位数字是原4位数的百位数字),如果新组成的两个十位数ab<cd,ab必须是奇数且不能被5整除,cd必须是偶数,同时两个新十位数字均不为零,则将满足此条件的4位数按从大到小的顺序存入数组b中,并要计算满足上述条件的4位数的个数cnt,最后调用写函数writeDat()把结果cnt及数组b中符合条件的4位数输出到OUT60.DAT文件中。
注意:部分源程序已给出。
程序中已定义数组:a[200],b[200],己定义变量:cnt。
请勿改动主函数main()、读函数readDat()和写函数writeDat()的内容。
试题程序;
#include<stdio.h>
#define MAX 200
int a[MAX],b[MAX] ,cnt=0; void jsVal( )
void readDat ()

int i;
FILE *fp;
fp= fopen ( "IN60. DAT", "r" );
for (i=0 ; i<MAX; i++)
fscanf(fp,"%d",&a[i]);
fclose(fp);
main()

int i;
readDat();
jsVal();
printf ( "满足条件的数=%d\n", cnt);
for(i=0;i<cnt;i++)
printf("%d\n",b[i]);
printf("\n");
writeDat ( );
writeDat ( )

FILE *fp;
int i;
fp=fopen("OUT60.DAT","w");
fprintf(fp,"%d\n",cnt);
for(i=0;i<cnt;i++)
fprintf(fp,"%d\n",b[i]);
fclose(fp);