单选题设函数f(x)在区间(0，1)内可导，f"(x)＞0，则在(0，1)内f(x)______．

单选题f(x)在(-∞，+∞)上连续，且f(x)＞0，则的单调性为()。

单选题若圆的方程是x2+y2=1，则它的右半圆(在第一象限和第四象限内的部分)的方程是______．A．B．C．D．E．

单选题曲线x2-2x+y2-3=0到直线3x+4y+5=0的最长距离是______。A．B．4C．5D．E．6

单选题半圆形闸门半径为R(米)，将其垂直放入水中，且直径与水面齐，设水密度ρ=1．若坐标原点取在圆心，x轴正向朝下，则闸门所受压力P为______A．．B．．C．．D．．

单选题一所四年制大学每年的毕业生七月份离校，新生九月份入学，该校2001年招生2000名，之后每年比上一年多招200名，则该校2007年九月底的在校学生有______．

单选题直角边之和为12的直角三角形面积最大值等于______．

单选题车间共有40人，某次技术操作考核的平均成绩为80分，其中男工平均成绩为83分，女工平均成绩为78分．该车间有女工( )． A．16人 B．18人 C．20人 D．24人 E．28人

单选题已知，那么=______。A．B．C．D．

单选题Mark Twain once observed that giving up smoking is easy. He knew, because he' d done it hundreds of times himself. Giving up for ever is a trifle more difficult, apparently, and it is well known that it is much more difficult for some people than for others. Why is this so? Few doctors believe any longer that it is simply a question of will power. And for those people that continue to view addicts as merely "weak", recent genetic research may force a rethink. A study conducted by Jacqueline Vink, of the Free University of Amsterdam, used a database called the Netherlands Twin Register to analyze the smoking habits of twins. Her results, published in the Pharmacogenomics Journal, suggest that an individual's degree of nicotine dependence, and even the number of cigarettes he smokes per day, are strongly genetically influenced. The Netherlands Twin Register is a voluntary database that contains details of some 7,000 pairs of adult twins (aged between 15 and 70) and 28,000 pairs of childhood twins. Such databases are prized by geneticists because they allow the comparison of identical twins (who share all their genes) with fraternal twins (who share half). In this case, however, Dr. Vink did not make use of that fact. For her, the database was merely a convenient repository of information. Instead of comparing identical and fraternal twins, she concentrated on the adult fraternal twins, most of whom had completed questionnaires about their habits, including smoking, and 536 of whom had given DNA samples to the register. The human genome is huge. It consists of billions of DNA "letters", some of which can be strung together to make sense (the genes) but many of which have either no function, or an unknown function. To follow what is going on, geneticists rely on markers they have identified within the genome. These are places where the genetic letters may vary between individuals. If a particular variant is routinely associated with a particular physical feature or a behavior pattern, it suggests that a particular version of a nearby gene is influencing that feature or behavior. Dr. Vink found four markers which seemed to be associated with smoking. They were on chromosomes 3, 0, 10 and 14, suggesting that at least four genes are involved. Dr. Vink hopes that finding genes responsible for nicotine dependence will make it possible to identify the causes of such dependence. That will help to classify smokers better (some are social smokers while others are physically addicted) and thus enable "quitting" programs to be customized. Results such as Dr. Vink's must be interpreted with care. Association studies, as such projects are known, have a disturbing habit of disappearing, as it were, in a puff of smoke when someone tries to replicate them. But if Dr. Vink really has exposed a genetic link with addiction, then Mark Twain's problem may eventually become a thing of the past.

单选题设f(x)=(1+x)ex，则f(x)( ) A．有极小值 B．有极大值 C．无极值 D．是否有极值不能确定

单选题设，则等于()A．-1B．0C．1D．2

单选题一抛物线以y轴为对称轴，且过点及原点，一直线L经过和点，则直线L被抛物线截得的线段的长度为()．

单选题Although ordinarily skeptical about the purity of Robinson's motives, in this instance Jenkins did not consider Robinson's generosity to be ______ consideration of personal gain. A. lacking in B. contrary to C. alloyed with D. mitigated by

单选题A．B．0C．ln2D．-ln2

单选题设f(x)是奇函数，除x=0外处处连续，x=0是其第一类间断点，则是______

单选题设f(cos2x)=sin2x，则等于()。A．1B．0C．D．-1

单选题甲仓存粮30吨，乙仓存粮40吨，要再往甲仓和乙仓共运去粮食80吨，使甲仓粮食是乙仓粮食数量的1.5倍，应运往乙仓的粮食是( )吨．

单选题若矩阵和对角矩阵相似，则a=