单选题设f(x)连续，且，已知f(1)=1，那么=______。A．B．C．e+1D．

单选题如果a，b，c是非零实数，且a+b+c=0，那么由此可知如下表达式的可能取值有______A.0B.1或-1C.2或-2D.0或-2E.-2

单选题已知数列{an}的前n项的和Sn=1一m2an，则此数列是()．

单选题设z=xexy，则

单选题设y(x)是四阶常系数线性微分方y(4)+y"=0的不恒等于零的解，且，则当x→0时y(x)关于无穷小量x的最高阶数是

单选题函数y=x2+bx+c，x∈[0，+∞)是单调函数的充要条件是______。 A．b≥0 B．b≤0 C．b＞0 D．b＜0

单选题A、B 两地相距 96km，甲、乙两辆车同时从 A 地出发匀速驶往 B 地。开车 1h 后，甲车在乙车前方 12km 处。 甲车比乙车早 40min 到达 B 地， 甲车的行车速度是 （ ）km/h。

单选题{{B}}Directions:{{/B}} There are 4 reading passages in this part. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C, and D. You should decide on the best choice and mark your answer on the ANSWER SHEET by blackening the corresponding letter in the brackets. In most sectors of the economy, it is the seller who attempts to act a potential buyer with various inducements of price, quality, and utility, and it is the buyer who makes the decision. In the health care industry, however, the doctor-patient relationship is a mirror image of the ordinary relationship between producer and consumer. Once an individual has chosen to see a physician, the physician usually makes all significant purchasing decisions: whether the patient should return "next Wednesday", whether X-rays are needed, whether drugs should be prescribed, etc. This is particularly significant in relation to hospital care. The physician must certify the need for hospitalization, determine what procedures will be performed, and announce when the patient may be discharged. The patient may be consulted about some of these decisions, but in the main it is the doctor's judgments that are final. Little wonder then that in the eyes of the hospital it is the physician who is the real "consumer". As a consequence, the medical staff represents the "power centre" in hospital policy and decision-making, not the administration. Although usually, there are in this situation four identifiable participants--the physician, the hospital, the patient and the payer (generally an insurance carrier or government) -- the physician makes the essential decision for all of them. The hospital becomes an extension of the physician, the payer generally meets most of the bona fide bills generated by the physician/ hospital, and for the most part, the patient plays a passive role. In routine or minor illensses, or just plain worries, the patient's options are, of course, much greater with respect to use and price. But in illnesses that are of some significance, such choice tends to evaporate. And it is for these illnesses that the bulk of the health care dollar is spent. We estimate that about 75 --80 percent of health care expenditures are determined by physicians. For this reason, economy measures directed at patients or the general public are relatively ineffective.

单选题当x＞0时，则的最小值为______．A．6B．C．D．E．以上都不对

单选题下列等式中，成立的是______A．B．C．D．

单选题在Rt△ABC中，已知AB=6，AC=8，∠A=90°，如果把Rt△ABC绕直线AC旋转一周得到一个圆锥，其表面积为S1；把Rt△ABC绕直线AB旋转一周得到另一个圆锥，其表面积为S2，那么S1:S2=( )． (A) 2:3 (B) 3:4 (C) 4:9 (D) 5:12

单选题对于n元二次型x T Ax，下述命题中正确的是

单选题t为何值时，方程组没有非零解，则

单选题设A为3阶矩阵，B=(β 1 ，β 2 ，β 3 )，β 1 为AX=0的解，β 2 不是AX=0的解，又r(AB)＜min{r(a)，r(B)}，则r(AB)=______．