单选题要得到函数的图像，只需将函数的图像上所有的点的()．

单选题以下结论正确的是( )． A.函数f(x)的导数不存在的点，一定不是f(x)的极值点 B.若x0为函数f(x)的驻点，则x0必为f(x)的极值点 C.若函数f(x)在点x0处有极值，且f'(x0)存在，则必有f'(x0)=0 D.若函数f(x)在点x0处连续，则f'(x0)一定存在

单选题把面积为3π，顶角为120°的扇形卷成一个圆锥，则圆锥体积为()．

单选题设f(x)在(-∞，+∞)内是可导的奇函数，则下列函数中是奇函数的是______。A．sinf'(x)B．C．D．

单选题在假设检验中，如果待检验的原假设为H 0 ，那么犯第二类错误是指

单选题设un＞0，n=1，2，…，若发散，收敛，则下列结论正确的是A．收敛，发散．B．发散，收敛．C．收敛．D．收敛．

单选题设函数f(x)=ln(2x+1)，则f(x)在x=0处的二阶导数f"(0)等于______。A．0B．C．-4D．2

单选题Work looks a better cure for poverty than welfare Especially as fewer and fewer countries will be able to afford to pay potential workers to stay at home a Victorian idea is back in favour: many poor people are better off when they are pulled back into the labour market. The idea revived first in the United States. There, in its harshest form, the unemployed work in exchange for welfare. But countries with governments to the left of America's, including Labour Australia and Socialist France, are now also exploring ways to link income support and employment policy. Coming from different directions, the right and the left are gradually finding new common ground. For the right, it seems deplorable to encourage the poor to rely on the state for cash, because they get hooked on government help and accustomed to being poor. For the left, it seems deplorable to allow workers to drop out of the job market for long periods, because it makes it harder for them to find new jobs. For both, the answer is to get the poor to work. Most industrial countries have a two-tier system of social protection: a social-security scheme, where workers and their bosses make regular contributions in exchange for payments to workers when they are unemployed, sick or retired; and a safety-net, to give some income to those poor people who have exhausted their social insurance or who have none The former is usually not means-tested but, for the unemployed, is of limited duration; the latter is almost always tied to income The public tends to approve of contributory benefits, which is what designers of such schemes intended. Safety-net benefits carry no such sense of entitlement, and are less popular. Yet they have grown more rapidly in large part because the 1980-82 recession increased the number of people of working age who had exhausted their right to contributory benefits. And an increasing proportion of the poor are people for whom the contributory systems were never designed: the young and lone mothers. In consequence, payments which carry a clear entitlement have become less significant, compared with those which appear to depend purely on state charity. The rise in the bill for the unpopular kind of social protection comes at a time when governments want to curb state spending. It comes, too, at a time when many countries have done almost everything they can think of to protect the poor. A decade ago many on the left argued that poverty was usually caused by circumstances outside the control of the poor—a lack of jobs, disability, old age, racial discrimination, broken marriages. One way or another, governments have tried to tackle most of these problems. Still the poor remain.

单选题Together,AndreaandBrianweighppounds;Brianweighs10poundsmorethanAndrea.BrianandAndrea'sdog,Cubby,weighspoundsmorethanAndrea.Intermsofp.whatisCubby'sweightinpounds?

单选题设则在它们各自的定义域上()．

单选题已知整数a，b，c满足不等式a 2 +b 2 +c 2 +43≤ab+9b+8c，则a的值等于______．

单选题函数f(x)=ln|(x-1)(x-2)(x-3)|的驻点个数为

单选题设又，则

单选题设f(x)在[a，b]上连续，则的值____。

单选题设f(x)=xlnx，则f(n)(x)(n≥2)等于()A．B．C．D．

单选题已知函数f(x)=|2x+1|+|2x-3|。若关于x的不等式f(x)＞a恒成立，则实数a的取值范围( )。

单选题设f(x)连续可导，且f(0)为f(x)的极值，则()

单选题某学习小组男女生共有8人，现从男生中选2人，从女生中选1人，分别担任三种不同的工作，共有90种不同的选法，则男女生人数为{{U}} {{/U}}。 A.男2人，女3人 B.男3人，女5人 C.男5人，女3人 D.男6人，女2人

单选题计算计算的值为().

单选题一个圆的半径为r，圆外点P到圆心O的距离h＞r，过P的圆的两条切线的切点为A和B．(1)求AB的长度．(2)求O到AB的距离d．