设区域D={(x，y)｜x2+y2≤4，x≥0，y≥0)，f(x)为D上正值连续函数，a，b为常数，则

计算累次积分：

设D={(x，y)｜0≤x＜+∞，0≤y＜+∞}，求

填空题In the following text, some sentences have been removed. For Questions (41-45), choose the most suitable one from the list A-G to fit into each of the numbered blank. There are two extra choices, which do not fit in any of the gaps. English has become the world's number one language in the 20th century. In every country where English is not the native language, especially in the Third World, people must strive to learn it to the best of their abilities, if they want to participate fully in the development of their countries. 41．______ A close examination reveals a great number of languages have fallen casualty to English. For example, it has wiped out Hawaiian, Welsh, Scotch Gaelic, Irish, native American languages, and many others. Luckily, some of these languages are now being revived, such as Hawaiian and Welsh, and these languages will live again, hopefully, if dedicated people continue their work of reviving them. 42．______If this situation continues, the native or official languages of these countries will certainly die within two or three generations. This phenomenon has been called linguistic genocide. A language dies if it is not fully used in most activities, particularly as a medium of instruction in schools. 43．______According to many studies, only around 20 to 25 percent of students in these countries can manage to learn the language of instruction (English) as well as basic subjects at the same time. Many leaders of these Third World countries are obsessed with English and for them English is everything. They seem to believe that if the students speak English, they are already knowledgeable. These leaders speak and write English much better than their national languages. If these leaders deliver speeches anywhere in the world they use English and they feel more at home with it and proud of their ability as well. The citizens of their countries do not understand their leaders' speeches because they are made in a foreign language. All the greatest countries of the world are great because they constantly use their own languages in all national development activities, including education. From a psychological point of view, those who are taught in their own language from the start will develop better self-confidence and self-reliance. From a linguistic point of view, the best brains can only be produced if students are educated in their own language from the start. 44. There is nothing wrong, however, in learning a foreign language at advanced levels of education. 45. [A] But many people are concerned that English's dominance will destroy native languages. [B] But the best thing to do is to have a good education in one's native language first, then go abroad to have a university education in a foreign language. [C] Suppose you work in a big firm and find English very important for your job because you often deal with foreign businessmen. Now you are looking for a place where you can improve your English, especially your spoken English. [D] Nonetheless, a world full of different languages will disappear if the present trend in many countries to use English to replace the national or official languages in education, trade and even politics continues. [E] Those who are taught in a foreign language from the start will tend to be imitators and lack self-confidence. They will tend to rely on foreign consultants. [F] Here are some advertisements about English language training from newspapers. You may find the information you need. [G] The Third World countries that are now using English as a medium of instruction are depriving 75 percent of their future leaders of a proper education.

将下列累次积分交换积分次序：

设D是由曲线y=x3与直线y=x在第一象限内围成的封闭区域，求

交换下列累次积分的积分顺序：

单选题Supporters of abortion rights held a lunch recently in honor of a momentous victory for their cause: 40 years ago, New York became the first state to fully legalize abortion. That 1970 law began to reduce the death and injury toll from back-alley abortions and set the stage for the Supreme Court's Roe v. Wade decision in 1973, which made abortion legal nationwide and recognized a constitutional right to privacy. But abortion-rights groups are newly anxious about new assaults on women's reproductive rights, including a fight over abortion that snarled the last days of the health care reform debate. Anti-abortion groups are newly emboldened. Kelli Conlin, head of Naral Pro-Choice New York, told guests at the lunch that "anti-choice forces are mobilizing in every single state to limit a woman's access to abortion in more insidious ways than we can imagine. " As Ms. Conlin was speaking, members of the Oklahoma House were getting ready to override vetoes of two punishing abortion measures. The state's Democratic governor, Brad Henry, rightly viewed these intrusions into women's lives and decision-making as unconstitutional. One of the measures, which seems destined to spawn copycat bills in other states, requires women to undergo an ultrasound before getting an abortion and further mandates that a doctor or technician set up the monitor so the woman can see it and hear a detailed description of the fetus. The other law grants protection from lawsuits to doctors who deliberately withhold fetal testing results that might affect a woman's decision about whether to carry her pregnancy to term. Several states have either passed or are considering bills that would ban abortion coverage in insurance plans sold through the state exchanges established by the federal health care law. A new Utah law criminalizes certain behavior by women that results in miscarriage. Embarking on a road that could lead to the Supreme Court, Nebraska last month banned most abortions at the 20th week of pregnancy based on a questionable theory of fetal pain. About two dozen states are looking at bills to increase counseling requirements or waiting periods prior to abortions. About 20 states are considering new ultrasound requirements. "One in three women in this country will have an abortion in her lifetime, and yet we're having exactly the same discussions and debates we were having forty years ago," Ms. Conlin said. Anti-abortion forces aim ultimately to make abortion illegal. So far, by reducing the number of abortion providers, making insurance coverage more expensive and harder to get, and throwing up other obstacles, they have primarily succeeded in making it harder for women of modest and meager means to obtain a safe and legal medical procedure. The painful decision to end a pregnancy should be made in private between a woman and her doctor—not in politically driven debate among members of Congress and state legislatures.

填空题设某产品的需求函数为Q=Q(p)，其对应价格P的弹性E p =0．2，则当需求量为10000件时，价格增加1元会使产品收益增加______元．

设f(x)在[a，b]上连续，求证：

设g(x)有连续的导数，g(0)=0，g’(0)=a≠0,f(a，y)在点(0，0)的某邻域内连续，则=()

计算二重积分及y轴为边界的无界区域．

设函数计算二重积分，其中D={(x，y)｜｜x｜+｜y｜≤2}．

填空题设x=e-x一f(x一2y)，且当y=0时，z=x2，则=________.

已知(axy 3 -y 2 cosx)dx+(1+bysinx+3x 2 y 2 )dy为某二元函数f(x，y)的全微分，则常数

设(r，θ)为极坐标，u=u(r，θ)具有二阶连续偏导数，并满足

计算二重积分

填空题设f(u，v)是二元可微函数

求曲线的一条切线l，使该曲线与切线l及直线x=0，x=2所围成图形面积最小．

计算其中D由曲线｜x｜+｜y｜=1所围成．