单选题A.条件(1)充分，但条件(2)不充分B.条件(2)充分，但条件(1)不充分C.条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分D.条件(1)充分，条件(2)也充分E.条件(1)和(2)单独都不充分，两个条件联合起来也不充分

单选题已知a，b，c，d为不等于零的实数，且a≠b，c≠d，ad+bc≠0，设m2=则有______．A．m1+m2+m3＞m1m2m3B．m1+m2+m3=m1m2m3C．m1+m2+m3＜m1m2m3D．E．m1+m2+m3与m1m2m3大小关系不确定

单选题一个等比数列前几项和Sn=abn+c，a≠0，b≠0且b≠1，a、b、c为常数，那么a，b，c必须满足( )． (A) a+b=0 (B) c+b=0 (C) a+c=0 (D) a+b+c=0

单选题Just how does a person arrive at an idea of the kind of person that he is? He develops this (1) of self through a gradual and complicated (2) which continues throughout life. The notion is an (3) that one establishes only with the help of others. (4) the elementary knowledge that one is short or tall is a comparative judgment that we cannot make (5) we have the opportunity to (6) ourselves with others. One's idea of qualities which are harder to (7) is even more dependent upon other people's ideas. Whether one is intelligent, or stupid; attractive, or ugly; these and many other ideas of the self are (8) from the reactions of people with whom we (9) This process of (10) the nature of the self from the reaction of others has been labeled the "Looking-glass Self" by Cooley, who carefully analyzed this psychological (11) of self-discovery. Just as the picture in the mirror gives an image of the physical self, (12) the perception of the reactions of others gives an image of the social self. We know, (13) , that we are good at certain things and not at others. This (14) came to us from the reactions of other persons, first our parents and then other individuals (15) in life. It should be remembered that, as other people's reactions could be (16) and understood in more than one way, the looking-glass self with which the individual (17) may easily differ from the image others have actually formed of his (18) Clearly, it is our perception of the responses of others and not their (19) responses that (20) our self-image, and these perceptions are often not accurate.

单选题的属于特征值λ=0的线性无关特征向量有______。A．0个B．1个C．2个D．3个

单选题设，则f(x)在(-∞，+∞)内(A)没有零点．(B)只有一个零点．(C)恰有两个零点．(D)恰有三个零点．

单选题已知关于x的一元二次方程8x2+(m+1)x+m-7＝0有两个负数根，那么实数 m的取值范围是( )。

单选题设事件A，B互不相容，则下列结论中，正确的是______。A．互不相容B．相容C．A，B相互独立D．P(A-B)=P(A)

单选题=______．A．1998B．11999C．2000D．2001

单选题[2016年12月]如图，在扇形AOB中，∠AOB=，OA=1，AC⊥OB，则阴影部分的面积为()。