单选题The teacher gave the students extra work because she was ______ by all the noise and talking in the classroom. A. interrupted B. degenerated C. terminated D. exasperated

单选题若E(XY)=E(X)E(Y)，则______．

单选题长途汽车从A站出发，匀速行驶，1 h后突然发生故障，车速降低了40%，到B站终点延误达3 h，若汽车能多跑50 km后，才发生故障，坚持行驶到B站能少延误1 h20 min，那么A、B两地相距( )k m．

单选题若f(x)=-f(-x)，在(0，+∞)内f'(x)＞0，f"(x)＞0，则f(x)在(-∞，0)内______．

单选题设A，B，C均为n阶矩阵，E为n阶单位矩阵，若B=E+AB，C=A+CA，则B-C为 (A) E． (B) -E． (C) A． (D) -A．

单选题For me, scientific knowledge is divided into mathematical sciences, natural sciences or sciences dealing with the natural world (physical and biological sciences), and sciences dealing with mankind (psychology, sociology, all the sciences of cultural achievements, every kind of historical knowledge). Apart from these sciences is philosophy, about which we will talk later. In the first place, all this is pure or theoretical knowledge, sought only for the purpose of understanding, in order to fulfill the need to understand that is intrinsic and con-substantial to man. What distinguishes man from animals is that he knows and needs to know. If man did not know that the world existed, and that the world was of a certain kind, that he was in the world and that he himself was of a certain kind, he wouldn't be man. The technical aspects or applications of knowledge are equally necessary for man and are of the greatest importance, because they also contribute to defining him as man and permit him to pursue a life increasingly more truly human. But even while enjoying the results of technical progress, man must defend the primacy and autonomy of pure knowledge. Knowledge sought directly for its practical applications will have immediate and foreseeable success, but not the kind of important result whose revolutionary scope is for the most part unforeseen, except by the imagination of the Utopians. Let me recall a well-known example. If the Greek mathematicians had not applied themselves to the investigation of conic section zealously and without the least suspicion that it might someday be useful, it would not have been possible centuries later to navigate far from shore. The first men to study the nature of electricity could not imagine that their experiments, carried on because o mere intellectual curiosity, would eventually lead to modern electrical technology, without which we can scarcely conceive o contemporary life. Pure knowledge is valuable for its own sake, because the human spirit cannot resign itself to ignorance. But, in addition, it is the foundation for practical results that would not have been reached if this knowledge had not been sought disinterestedly.

单选题设函数f(x)在|x|＜δ内有定义且|f(x)|≤x 2 ，则f(x)在x=0处______．

单选题已知abc＜0，a+b+c=0，则______．

单选题设，当x→0时，与f(x)等价的无穷小量是()．

单选题设X为连续型随机变量，方差存在，则对任意常数C和ε＞0，必有( )．

单选题若2a2+3a-b=4，则=()．

单选题设y=sin2x，则y"=______．

单选题毛泽东思想关于党的建设理论最核心的内容和最主要的特点是______。 A．着重于从思想上建设 B．加强党的组织建设 C．加强党员的党性修养 D．保持党的优良作风

单选题设有以下命题：①若收敛，则收敛；②若收敛，则收敛；③若，则发散；④若收敛，则都收敛．则以上命题中正确的是

单选题设A，B为两个随机事件，且AB，则A．B．C．D．

单选题设函数f(x)=x2-1，则f(x+1)=(　　)

单选题下列极限中，正确的是______A．B．C．D．

单选题某人用2400元买进甲、乙股票各若干组．在甲股票升值15%、乙股票下跌10%时全部抛出，他共赚得135元，则此人购买甲股票的金额与乙股票的金额之比为______．

单选题设|x-2|+|y+3|＝1，则满足此等式的整数x与y的值分别为( )．

单选题当x≠-1和x≠-2时，恒成立，则______．