单选题a 1 b 2 =15 (1)-9，a 1 ，-1成等差数列 (2)一9，b 1 ，b 2 ，b 3 ，-1成等比数列

单选题求函数的值域为______．

单选题设则f(x)在x=0处______

单选题(m为非0常数)等于______．A．mB．1C．m2D．

单选题设f 在(-∞，+∞)上有定义，x 0 ≠0为函数f(x)的极大值点，则______．

单选题[2010年1月]已知数列{a n }为等差数列，公差为d，a 1 +a 2 +a 3 +a 4 =12，则a 4 =0。 (1)d=一2； (2)a 2 +a 4 =4。

单选题一项工程如果由甲施工队单独承包，要210天完成，如果由甲、乙两个施工队一起承包，要84天完成，由甲、丙两个施工队一起承包，要105天完成，则如果三个施工队一起做，工期为( )．

单选题某数的绝对值和算术平方根等于它本身，这个数必为______ A.2或1 B.2或0 C.1或-1 D.1或0 E.-1或0

单选题如果图1中给出了平面直角坐标系中直线l:y=ax+b的图像，那么坐标为(a，b)的点在()．

单选题已知f(x)的一个原函数为ln2x，则=______。A．0B．1C．2D．ln2

单选题在下列微分方程中，以y=C1ex+C2cos2x+C3sin2x(C1，C2，C3为任意常数)为通解的是 (A) y″′+y″-4y′-4y=0． (B) y″′+y″+4y′-4y=0． (C) y″′-y″-4y′+4y=0． (D) y″′一y″+4y′-4y=0．

单选题设．则正确的是A．．B．．C．．D．．

单选题Within 80 years, some scientists estimate, the world must produce more than eight times the present world food supply. The productiveness of the sea raises our hopes for an adequate food supply in the future. Aided by men of science, we have set forth to find out that 70 percent of the earth remains unexplored--the ocean depths. Thus, we may better discover and utilize the sea's natural products for the world's hungry. It is fish protein concentrate that is sought from the seas. By utilizing the unharvested fish in United States waters alone, enough fish protein concentrate can be obtained to provide supplemental animal protein for more than one billion people for one year at the cost of less than half a cent per day per person. The malnutrition of children is terribly tragic. But the crime lies in society's unrestrained breeding, not in its negligence in producing fish powder. But wherever the population projects are carefully considered, the answer to the problem is something like this: There are few projects that could do more to raise the nutritional level of mankind than a full-scale scientific effort to develop the resources of the sea. Each year some thirty million tons of food products are taken from the sea, which account for 12 percent of the world's animal proteins. Nations with their swelling populations must push forward into the sea frontiers for food supplies. Private industry must step up its marine research and the federal government must make new attacks on the problems of marine research development. There is a tone of desperateness in all these designs on the sea. But what is most startling is the assumption that the seas are an untouched resource. The fact is that the seas have been, and are being, hurt directly and indirectly, by the same forces that have abused the land. In the broad pattern of ecological relationships the seas are not separable from what happens on the land. The poisons that pollute the soil and the air bring in massive doses into the "continental shelf" waters. The dirt and pollution that spills from our urban sewers and industrial out falls despoil our bays and coastal waters. All the border seas are already heavily polluted by the same exploitation drives that have undermined the quality of life on land.