单选题装某台需要甲、乙、丙三种部件各一件，现仓库中存有这三种部件共270件，分别用甲、乙，丙库存件数的来装配若干台机器，那么原来存有丙种部件()件．

单选题已知若α1，α2是矩阵A属于特征值λ=1的线性无关的特征向量，α3是矩阵A属于特征值λ=2的特征向量，则矩阵P不能是______

单选题两个半径都为r的圆盘的圆心间的距离也是r，则它们的公共部分的面积为()．

单选题The increasingly high rates of juvenile delinquency are a great problem in modem society. More and more people are paying special attention to it. When it comes to the reasons, here are two of them. Modem youth are more revolutionary and more independent than the elder generation. When this tendency goes to an extreme, problems arise. Some of the young want to throw away all the traditional principles and beliefs, most of which are very good for self-cultivation. They are reluctant to listen to the advice from elder generation. If they behave in the way, as they like, they might commit crimes without realizing it. Studies also show that juvenile-delinquency rates are twice as high for youngsters from single-parent homes as for those in traditional households. Children in single-parent families are taken less care of and thus have feelings of being neglected, discriminated and isolated. The lack of parental love makes them hostile and cynical towards the society. There are several ways to prevent the youth from committing crimes. School education plays an important role to teach traditional beliefs. Books and programs should be in good quality. There should be more educational books and programs for young children to tell them how to distinguish the right from the wrong. Also, mutual understanding between parents and children is also very important. Parental supervision and guidance are a key factor of self-cultivation in lifetime. The two generations need to smooth away disagreement. Parents can spend much time staying with their children and patiently carry out the duty of family education. And others are starting to pay attention to another problem in modern society that may underline all sorts of crimes, including juvenile delinquency, though it is believed that the development of information technology has made the world smaller. Modern people have greater tensions so that they have less time to communicate with each other. More and more people are living in urban areas, where life is in a quick rhythm. Due to fierce competition, which is the most important reason of all, city dwellers have to be working hard in order to keep up with the steps of city life. Everybody is busy all the time. Work pressures deprive them of a casual way of life. Moreover, living in apartments in different blocks, people are isolated from each other. It is not convenient for them to meet each other freely.

单选题总体X～N(μ，52)，则总体参数μ的置信度为1-α的置信区间的长度______。 A．与α无关 B．随α的增加而增加 C．随α的增大而减少 D．与α有关但与α的增减性无关

单选题方程x 2 +y 2 -z 2 =0表示的二次曲面是______

单选题由新民主主义向社会主义转变的根本政治条件是______。 A．坚持马克思列宁主义、毛泽东思想的指导 B．坚持无产阶级及其政党的领导 C．坚持人民民主专政 D．坚持人民代表大会制度

单选题若三次多项式g(x)满足g(-1)=g(0)=g(2)=0，g(1)=4，多项式f(x)=x 4 -x 2 +1，则3g(x)-4f(x)被x-1除的余式为______．

单选题下列极限计算正确的是()

单选题下列函数在指定区间上满足罗尔中值定理条件的是()。

单选题甲见候车室的椅子上坐着一女子和一男子，他们面前放着一手提箱，男子在睡觉，女子在看报。甲以为手提箱是该男子的，遂提一只相同的手提箱走上前去，将手提箱互换，被女子发现。手提箱实际上是该女子的，她一直在紧盯着这只箱子。箱内财物计人民币4000元。甲的行为构成( )。 A．盗窃罪 B．诈骗罪 C．抢夺罪 D．侵占罪

单选题若下列各极限都存在，其中等式不成立的是______A．B．C．D．

单选题设f(x)为连续的奇函数，则等于{{U}}{{/U}}．A．2af(x)B．C．0D．f(a)-f(-a)

单选题5个不同的数，两两之和依次等于3，4，5，6，7，8，11，12，13，15，这5个数的平均值是______．

单选题设方程3x2+mx+5=0的两个实根x1，x2满足则m的值为______．

单选题设A、B为两随机事件，且，则下列结论中肯定正确的是______．

单选题设函数f(x)在闭区间[a，b]上连续，则由曲线y=f(x)与直线x=a，x=b，y=0所围成图形的面积为( )

单选题社会主义精神文明建设的目标是______。 A．引导人们树立正确的人生观、世界观、价值观 B．弘扬爱国主义的精神 C．面向现代化、面向世界、面向未来的，民族的、科学的、大众的文化 D．培养有理想、有道德、有文化、有纪律的公民

单选题设X1，X2，…，Xn+1是取自正态总体N(0，σ2)的简单随机样本，记则