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A wheel is any dish like object that can be used for transportation or in machinery. To be useful, a wheel must revolve (1) an axle, which is normally a shaft attached (2) the wheel’s center.No one is exactly sure when the wheel was first (3) . But it is thought to have been in use during the early Bronze Age in the Tigris-Euphrates Valley in the Middle East— (4) Iraq is located today. We know that ancient people there used (5) . These and other wheeled vehicles are shown in artwork from the area (6) back to 3500 B.C.How were such (7) developed The idea began when people placed logs as rollers under a platform. They were used to (8) heavy loads. The center of the logs may have been partly hewn, or carved away, (9) a narrow axle between solid, thick wheels at each end. Some ancient Middle East people even wrapped leather tires around the solid wooden wheels attached to (10) carts.Probably the first way (11) wheels were used other than for transportation was in pottery making. (12) beautiful and useful pieces of pottery, a potter puts a lump of clay on a horizontally placed wheel which is attached to an axle. (13) the potter sits facing the wheel and makes it spin, using a foot pedal. The potter molds the clay, using both hands (14) fingers, as the wheel spins. Thus the clay is (15) . Various objects (16) bowls, plates, vases, and cups are produced in this manner.The wheel and axle also have other (17) . They are part of many (18) . An axle attached to a wheel, so that both spin at the same time, permits the use of small amounts of force to (19) very heavy load. This wheel-and-axle principle is used in all weight-lifting devices, such as cranes, hoists, and elevators. For example, by pulling a rope wrapped around the rim of a wheel, a person can lift a massive object with only a (20) amount of effort. 9().
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已知在文件IN.DAT中存有100个产品销售记录，每个产品销售记录由产品代码dm(字符型4位)、产品名称mc(字符型10位)、单价dj(整型)、数量sl(整型)、金额je(长整型)5部分组成。其中，金额=单价×数量。函数ReadDat()是读取100个销售记录并存入结构数组sell中。请编制函数SortDat()，其功能要求如下：按金额从小到大进行排列，若金额相等，则按产品代码从小到大进行排列，最终结果仍存入结构数组sell中，最后调用函数WriteDat()把结构输出到文件OUT1.DAT中。 注意：部门源程序已给出。请勿改动主函数main()、读数据函数ReadDat()和输出数据函数WriteDat()的内容。 试题程序： #include＜stdio.h＞ #include＜string.h＞ #include＜conio.h＞ #include＜stdlib.h＞ #define MAX 100 typedef struct char dm[5]；/*产品代码*/ char mc[11]；/*产品名称*/ int dj；/*单价*/ int sl；/*数量*/ long je；/*金额*/ PRO； PRO sell[MAX]； void ReadDat()； void WriteDat()； void SortDat() void main() memset(sell，0，sizeof(sell))； ReadDat()； SortDat()； WriteDat()： void ReadDat() FILE*fp； char str[80]，ch[11]； int i； fp=fopen("IN.DAT"，"r")； for(i=0；i＜100；i++) fgets(str，80，fp)； memcpy(sell[i].dm，str，4)； memcpy(sell[i].me，str+4，10)； memcpy(ch，str+14，4)；ch[4]=0； sell[i].dj=atoi(ch)； memcpy(ch，str+18，5)；ch[5]=0； sell[i].sl=atoi(ch)； sell[i].je=(long)sell[i].dj*sell[i].sl； fclose(fp)； void WriteDat() FILE*fp； int i； fp=fopen("OUT1.DAT"，"w")； for(i=0：i＜100；i++) printf("%s%s%4d%5d%5d\n"，sell[i].dm，sell[i].mc，sell[i].dj，sell[i].sl，sell[i].je)； fprintf(fp，"%s%s%4d%5d%5d\n"，sell[i].dm，sell[i].mc，sell[i].dj，sell[i].sl，sell[i].je)； ｝ fclose(fP)； ｝
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我国“八五”期间国民生产总值年均增长12.0％，其中沿海12省平均增长速度高达16.5％，内陆省(区、市)平均为9.2％。1995年国民生产总值达 57650亿元，提前实现了国民生产总值比1980年翻两番的战略目标。全国“七五”期间第一、二、三产业占国民经济总产值比重分别为：26.3％、43.3％、30.4％。“八五”期间第一、二、三产业占国民经济总产值的比重，与“七五”期间相比，第一产业下降了4.9个百分点，第二产业提高了2.7个百分点，第三产业上升了2.2个百分点。 沿海12省(区、市)国民生产总值年均增长速度比全国年均增长速度高多少个百分点( )
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