单选题钱袋中装有伍分和壹角的硬币若干，则壹角硬币的个数比伍分硬币的个数少． (1)伍分和壹角硬币共有伍元 (2)将相当于伍分硬币数目一半的壹角硬币从袋中取出，钱袋中恰剩3元

单选题f(x)在(-∞，+∞)内是以4为周期的可导函数，且，则f'(9)=______。A．B．0C．-1D．以上都不正确

单选题设f(x)在[0，1]上连续，又，则A.F(x+π)＞F(x)(x∈(-∞，+∞))．B.F(x+π)＜F(x)(x∈(-∞，+∞))．C.F(x+π)=F(x)(x∈(-∞，+∞))．D.x＞0时F(x+π)＞F(x)，x＜0时F(x+π)＜F(x)．

单选题如果a，b，c是三个任意整数，那么______A.都不是整数B.至少有两个整数C.至少有一个整数D.都是整数E.以上答案均不正确

单选题设存在正整数N，使得n＞N时，有an≤A≤bn，且则______A．但不一定存在．B．都存在，但不一定相等．C．都不一定存在．D．

单选题有一个数，除以4余3，除以5余4，除以7余6．这个数最小是m，则m的各个数位之和为______．

单选题将一枚均匀的硬币接连抛2次，以A表示事件“正面最多出现一次”，以B表示事件“正面和反面各至少出现一次”，则( )

单选题[2016年12月]某机构向12位教师征题，共征集到5种题型的试题52道。则能确定供题教师的人数。 (1)每位供题教师提供试题数相同； (2)每位供题教师提供的题型不超过2种。

单选题等差数列{a n }的前n项和S n 取最大值时，n的值是21． (1)a 1 ＞0，5a 4 =3a 9 ． (2)a 1 ＞0，3a 4 =5a 11 ．

单选题方程y"-3y'+2y=xe2x的待定特解y*应取( )．

单选题 The question of whether war is inevitable is one which has concerned many of the world's great writers. Before considering this question, it will be useful to introduce some related concepts. Conflict, defined as opposition among social entities (实体) directed against one another, is distinguished from competition, defined as opposition among social entities independently striving for something which is in inadequate supply. Competitors may not be aware of one another, while the parties to a conflict are. Conflict and competition are both categories of opposition, which has been defined as a process by which soical entities function in the disservice of one another. Opposition is thus contrasted with cooperation, the process by which social entities function in the disservice of one another. These definitions are necessary because it is important to emphasize that competition between individuals or groups is inevitable in a world of limited resources, but conflict is not. Conflict, nevertheless, is very likely to occur, and is probably an essential and desirable element of human societies. Many authors have argued for the inevitability of war from the premise that in the struggle for existence among animal species, only the fittest survive. In general, however, this struggle in nature is competition, not conflict. Social animals, such as monkeys and cattle, fight to win or maintain leadership of the group. The struggle for existence occurs not in such fights, but in the competition for limited feeding areas and for the occupancy of areas free from meat eating animals. Those who fail in this competition starve to death or become victims to other species. This struggle for existence does not resemble human war, but rather the competition of individuals for jobs, markets, and materials. The essence of the struggle is the competition for the necessities of life that are insufficient to satisfy all. Among nations there is competition in developing resources, trades, skills, and a satisfactory way of life. The successful nations grow and prosper, the unsuccessful decline. While it is true that this competition may include efforts to expand territory at the expense of others, and thus lead to conflict, it cannot be said that, war-like conflict among nations is inevitable, although competition is.

单选题已知关于x的方程x 2 一6x+(a一2)∣x一3∣+9—2a=0有两个不同的实数根，则系数a的取值范围是( )．

单选题两相似三角形△ABC与△A"B"C"的对应中线之比为3：2，若S △ABC =a+3，S △A"B"C" =a-3则a=( )。

单选题在△ABC中，若c-a等于AC边上的高h，则等于______。A．-1B．C．D．1

单选题已知，，，则______．

单选题设an＞0，n=1，2，3，…，若发散，收敛，则下列结论正确的是