一个栈的入栈序列A,B,C,则栈的不可能的输出序列是 (37) 。
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为了提高测试效率,应该 (51) 。
A. 随机地选取测试数据
B. 取一切可能的数据作为测试数据
C. 在完成全部编码以后开始软件的测试
D. 选择错误可能性大的数据作为测试数据
案例分析题数据结构被形式地定义为(K,R),其中K是()的有限集合,R是K上()的有限集合。 数据结构被形式地定义为(K,R),其中K是()的有限集合。
A. 算法
B. 数据元素
C. 数据操作
D. 逻辑结构
Some pessimistic experts feel that the automobile is bound to fall into disuse. They see a day in the not-mo-distant future when all autos will be abandoned and allowed to rust. Other authorities, however, think the auto is here to stay. They hold that the car will remain a leading means of travel in the foreseeable future. The motorcar will undoubtedly change significantly over the next 30 years. It should become smaller, safer, and more economical, and should not be powered by the gasoline engine. The car of the future should be far more pollution-free than present types. Regardless of its power source, the auto in the future will still be the main problem in urban traffic congestion (拥挤). One proposed solution to this problem is the automated highway system. When the auto enters the highway system, a retractable (可伸缩的) arm will drop from the auto and make contact with a rail, which is similar to those powering subway trains electrically. Once attached to the rail, the car will become electrically powered from the system, and control of the vehicle will pass to a central computer. The computer will then monitor all of the car’s movements. The driver will use a telephone to dial instructions about his destination into the system. The computer will calculate the best route, and reserve space for the car all the way to the correct exit from the highway. The driver will then be free to relax and wak for the buzzer (蜂鸣器) that will warn of his coming exit. It is estimated that an automated highway will be able to handle 10,000 vehicles per hour, compared with the 1,400 to 2,000 vehicles that can be carried by a present-day highway. In an automated highway system, all the driver needs to do is ______.
A. keep in the right lane
B. wait to arrive at his destination
C. keep in constant touch with the computer center
D. inform the system of his destination by phone
2007年,全国研究与试验发展(R&D)经费总支出为3710.2亿元,增长23.5%,研究与试验发展(R&D)经费投入强度(与国内生产总值之比)为1.49%。按研究与试验发展人员(全时工作量)计算的人均经费支出为21.4万元,比上年增加1.4万元。 分活动类型看,基础研究经费支出为174.5亿元,比上年增长12%;应用研究经费支出为492.9亿元,增长0.8%;试验发展经费支出3042.8亿元,增长29.5%。基础研究、应用研究、试验发展经费支出所占比重分别为4.7%、13.3%和82%。 分执行部门看,各类企业经费支出为2681.9亿元,比上年增长25.6%;政府部门属研究机构经费支出687.9亿元,增长21.3%;高等学校经费支出314.7亿元,增长13.7%。企业、政府部门属研究机构、高等学校经费支出占全国总支出的比重分别为72.3%、18.5%和8.5%。 分产业部门看,八大行业的研究与试验发展(R&D)经费投入强度(与主营业务收入之比)超过1%。专用设备制造业为1.95%,医药制造业为1.82%,通用设备制造业为1.53%,电气机械及器材制造业为1.42%,交通运输设备制造业为1.41%,橡胶制品业为1.28%,通信设备、计算机及其他电子设备制造业为1.15%,仪器仪表及文化、办公用机械制造业为1.03%。 分地区看,研究与试验发展(R&D)经费支出超过100亿元的有北京、江苏、广东、山东、上海、浙江、辽宁、四川、陕西、天津、湖北和河南共12个省(市),共支出2994.6亿元,占全国经费总支出的80.7%。研究与试验发展(R&D)经费投入强度(与地区生产总值之比)达到或超过全国水平的有北京、上海、天津、陕西、江苏、浙江和辽宁7个省(市)。 2007年,研究与试验发展经费支出超过100亿元,但经费投入强度没有达到或超过全国水平的共有几个省市?______
A. 4个
B. 5个
C. 6个
D. 7个