单选题已知x 1 ，x 2 是方程x 2 +m 2 x+n=0的两实根，y 1 ，y 2 是方程y 2 +5my+7=0的两实根，且x 1 -y 1 =2，x 2 -y 2 =2，则m，n的值分别为______．

单选题若，则k=()A．1B．3C．D．任意实数

单选题方程(x+1)(y2+1)dx+y2x2dy=0是______．

单选题直线被圆x2-4x+y2+2y=20截得弦为AB，则AB的长度为______．

单选题直线y=x+b与抛物线x2=2y交于A，B两点，O为坐标原点，且OA⊥OB，则b的值为______。 A．2 B．-2 C．1 D．-1

单选题一件夹克标价为a元，现按标价7折出售，则售价用代数式表示为( )元

单选题设n阶方阵A=(α 1 ，α 2 ，…，α n )，B=(β 1 ，β 2 ，…，β n )，AB=(γ 1 ，γ 2 ，…，γ n )，记向量组(Ⅰ)：α 1 ，α 2 ，…，α n ，(Ⅱ)：β 1 ，β 2 ，…，β n ，(Ⅲ)：γ 1 ，γ 2 ，…，γ n ，如果向量组(Ⅲ)线性无关，则______

单选题有两个半径为6cm、8cm，深度相等的圆柱形容器甲和乙，把装满容器甲里的水倒入容器乙里，水深比容器深度的低1cm，那么容器的深度为______cm。A．9B．9.6C．10D．12

单选题函数z=x 3 +y 3 -3x 2 -3y 2 的极小值点是______

单选题函数z=3x2y+2xy3在点(1，1)处的全微分dz|(1，1)等于 A.4dx-3dy B.4dx+3dy C.8dx+9dy D.8dx-9dy

单选题 Few people would defend the Victorian attitude to children, but if you were a parent in those days, at least you knew where you stood: children were to be seen and not heard. Freud and company did away with all that and parents have been bewildered ever since. The child's happiness is all-important, the psychologists say, but what about the parents' happiness? Parents suffer continually from fear and guilt while their children gaily romp about pulling the place apart. A good "old-fashioned" spanking is out of the question: no modern child-rearing manual would permit such barbarity. The trouble is you are not allowed even to shout. Who knows what deep psychological wounds you might inflict? The poor child may never recover from the dreadful traumatic experience. So it is that parents bend over backwards to avoid giving their children complexes which a hundred years ago hadn't even been heard of. Certainly a child needs love, and a lot of it. But the excessive permissiveness of modern parents is surely doing more harm than good. Psychologists have succeeded in undermining parents' confidence in their own authority. And it hasn't taken children long to get wind of the fact. In addition to the great modern classics on childcare, there are countless articles in magazines and newspapers. With so much unsolicited advice flying about, mum and dad just don't know what to do any more. In the end, they do nothing at all. So, from early childhood, the kids are in charge and parents' lives are regulated according to the needs of heir offspring. When the little dears develop into teenagers, they take complete control. Lax authority over the years makes adolescent rebellion against parents all the more violent. If the young people are going to have a party, for instance, parents are asked to leave the house. Their presence merely spoils the fun. What else can the poor parents do but obey'? Children are hardy creatures (far hardier than the psychologists would have us believe) and most of them survive the harmful influence of extreme permissiveness which is the normal condition in the modern household. But a great many do not. The spread of juvenile delinquency in our own age is largely due to parental laxity. Mother, believing that little Johnny can look after himself, is not at home when he returns from school, so little Johnny roams the streets. The dividing-line between permissiveness and sheer negligence is very fine 'indeed. The psychologists have much to answer for. They should keep their mouths shut and let parents get on with the job. And if children are knocked about a little bit in the process, it may not really matter too much. At least this will help them to develop vigorous views of their own and give them something positive to react against. Perhaps there's some truth in the idea that children who have had a surfeit of happiness in their childhood appear like stodgy puddings and fail to make a success of life.

单选题请你想好一个数，将它加5，将其结果乘以2，再减去4，将其结果除以2，再减去你想好的那个数，最后的结果等于______。A．B．1C．D．3

单选题P(a，b)是第一象限内的矩形ABCD(含边界)中的一个动点，A，B，C，D的坐标如图所示，则的最大值与最小值依次是______。A．B．C．D．