单选题过原点的直线与圆x2+y2+4x+3=0相切，若切点在第三象限，则该直线的方程是______．A．B．C．D．E．以上答案均不正确

单选题设函数y=y(x)由参数方程确定，则______A．B．C．D．

单选题若方程的两根分别为a，，则方程的根是______．A．B．C．D．E．以上均不对

单选题若直线l将圆x2+y2-2x-4y=0平分且不通过第四象限，则l的斜率的取值范围是______．A．[0，2]B．[0，1]C．D．E．[0，1)

单选题Whoever said that victory has many fathers and defeat is an orphan, surely had never heard of the World Trade Organization (WTO). In the case of the hapless multilateral trade body and its long suffering representatives, the total failure of the opening meeting of the so called Millennium trade round has lots of people boasting of their roles in the violent physical struggle. Well. That's just brilliant. They are proud of being part of a movement that wants to wreck the most important engine of economic growth, prosperity and overall global rising living standards we have--the freedom of trade and movement of people and goods between nations. The 135-member WTO is composed of sovereign governments wishing to further this goal and ease the settlement of international trade disputes. From the sounds emanating from Seattle, though, it would now seem the WTO has now replaced the Trilateral Commission and the Freemasons as candidate No. 1 to take over the World. Everybody has his favorite Seattle story. The city's police chief will have plenty of time to think about his, having now resigned in disgrace over the loss of control of downtown Seattle. The Seattle business community may be more inclined to brood over theirs--the poor fools invested $ 9 million to attract the meeting to their fine city. What stands out more? I would nominate the union of steel workers who were marching in protest. It's an image that will boggle the mind for years to come. The debate now is over just how effective this anti-globalist coalition will turn out to be. In the heat of the moment, it always looks as though the world as we know it is coming to an end. But the overwhelming likelihood is that we have not actually seen a replay of the anti Vietnam War movement, which had much clearer focus, obviously, though its consequences were far-reaching. How long, after all, can you protest against cheap imports when those same imports are all over your house? No, the real reason for the disaster in Seattle is political, and reports coming out of the meeting point to President Clinton as a major culprit. Which may be both good and bad. Taking the long view, other trade rounds have had difficult beginnings, too. It took years to get the Uruguay Round under way, which finally happened in 1986. Thankfully, we will soon be electing another president, and it should be someone whose actions match his rhetoric. Still, it is a disgrace that the world's greatest trading nation, i.e. the United States, is currently led by a man whose motivations are so narrowly political and egocentric that he has now wrecked any chance of entering the history books as a champion of free trade.

单选题如图7—1，AB是半圆的直径，O是圆心，AB=12，从AB延长线上一点P作⊙O的切线，与⊙O切于D，DE⊥AB于E，若AE：EB=3：1，则图中阴影部分面积为()．

单选题如果α 1 ,α 2 ,α 3 分别是AABC的∠A，∠B，∠C的外角，则∠BAC=20°． (1)α 1 ,α 2 ,α 3 =4：2：3(2)α 1 ,α 2 ,α 3 =2：4：3

单选题设f(x)与g(x)在x=a处均为极大值．又设F(x)=f(x)g(x)，则F(x)在x=a处______

单选题=______。A．πB．C．1D．

单选题设an是首项为1的正项数列，且(n=1，2，3，…)，那么它的通项公式是______。A．B．C．D．an=2n

单选题设f(x)在(-∞，+∞)内有定义，且=a，g(x)=，则______A．x=0必是g(x)的第一类间断点．B．x=0必是g(x)的第二类间断点．C．x=0必是g(x)的连续点．D．g(x)在点x=0处的连续性与a的取值有关．

单选题设A是一个n×n矩阵，交换A的第i行、第j行，然后再交换其第i列、第j列，所得矩阵为B，考虑命题：①|A|=|B|；②r(A)=r(B)；③A、B的行向量组等价；④A与B为相似矩阵，则以上命题成立的个数为______。

单选题已知矩阵，其中a＞b＞c＞0。①ATX=0只有零解②ATAX=0有无穷多解③，AX=b有无穷多解④，ATX=b有唯一解则以上命题中，正确的命题共有______。A．0个B．1个C．2个D．3个