单选题设A为n阶矩阵，且满足A2-A=6E，则矩阵A-3E和2E+A必定 (A) 都为可逆矩阵． (B) 都是不可逆矩阵． (C) 至少有一个为零矩阵． (D) 最多有一个为可逆矩阵．

单选题，则f(x)在______

单选题设f(x)=|x|sin 2 x，则使f (n) (0)存在的最高阶数n=

单选题一商店把某商品按标价的9折出售，仍可获利20%，若该商品进价为每件2l元，则该商品每件的标价为( )元．

单选题Henry Kissinger may be the most successful, certainly the most flamboyant, Secretary of State to hold that office in modern times. When he was appointed in the late 1960's, there were no American ties with Communist China, Vietnam and Berlin seemed ready to draw the United States into a third world war, and Russia was seen as "the enemy". But all this has changed, and Henry Kissinger caused much of the change; in 1971, he made his first trip to China, a trip that was the beginning of the current ties between the United States and China. He brought the United States and Russia closer together on major issues by the policy he called "detente", literally meaning a relaxation. His philosophy was always to talk and to bring together. With these two policies, Kissinger did much to draw attention away from any possible Russia-American friction. In 1973 he made his first visit to Egypt. Here he was able to begin U.S. relations with Egypt. He used his contact later to begin the sort of talks that the American press called "shuttle diplomacy". For ninety-nine days, he "shuttled" back and forth on flights between Cairo and Jerusalem to work out a step-by-step withdrawal of Israeli troops from the Sinai desert. His wit, his careful approach to detail, and his presence made "shuttle diplomacy" work. It was the only successful approach to Mid-east peace in the thirty years since the state of Israel was founded. Another major work was the Strategic Arms Limitation Talk. Though his term in office passed with the treaty unsigned, Kissinger left a draft of the treaty to which the Russians had already agreed. The SALT treaty spelled out a one-tenth reduction in nuclear arms, a major accomplishment by any standard, even if one does not consider all the other conditions and limitations included in the treaty. Even though he successfully helped bring an end to the Vietnam War, Kissinger's final days in office were affected, as was the entire executive branch in one way or another, by the scandals of the Nixon White House. Kissinger's critics point to his role in placing wiretaps on the phones of reporters and officials and to what they consider his "high-handed" approach to setting foreign policy. But Kissinger, during the last few months of the Nixon presidency, limited the effects of American domestic problems on our foreign policy. He continued talks in the Middle East. He continued close contact with the Soviet Union. History will decide in the final view, as Kissinger--and many presidents--often said, on the value of his service. Whatever they decide, whether his actions are finally to be considered wise or foolish, he had a personal vision that will be difficult to match. (459 words)Notes: work out 制定。spell out 清楚地说明。wiretap 窃听(电话)。scandal 丑闻。

单选题若函数f(x)是周期为6的奇函数，则的值等于()．

单选题7个人站成一排，其中甲乙两人中间恰好间隔两人的排法有______种．

单选题在空间直角坐标系中，方程x 2 十z 2 =z的图形是______．

单选题设A是m×n矩阵，B是n×m矩阵，则线性方程组(AB)X=0( )． (A) 当m＜n时仅有零解 (B) 当m＜n时必有非零解 (C) 当m＞n时仅有零解 (D) 当m＞n时必有非零解

单选题设曲线y=y(x)上点P(0,4)处的切线垂直于直线x-2y+5=0，且满足微分方程y"+2y'+y=0，则此曲线方程为

单选题设有直线当直线l1与l2平行时，λ=____

单选题某商场的营业额2005年、2006年分别比2004年、上升了10%，而2007年、2008年连续两年平均每年比上一年降低了10%，那么2008年比2004年的营业额( )．

单选题（　）

单选题展开式中的常数项是______。

单选题方程根的个数为()．A．0B．1C．2D．3

单选题设a＞0＞b＞c，a+b+c=1，，则M，N，P之间的关系是______

单选题等差数列{an}中，若a1=2，a3=6，则a7=（　　）

单选题已知f(x)是(-∞，+∞)上的单调增加函数，则F(x)=e-f(x)是______ A.单调增加 B.单调减少 C.不单调但有界 D.不单调但无界

单选题当x→0+时，______与x是等价无穷小量．A．B．ln(1-x)C．D．x2(x+1)

单选题掷两粒骰子，出现点数之和为5的概率为()