单选题The custom is ______ in the belief that a new pregnancy—through its detrimental effect on breastfeeding—would endanger the mother's health.

单选题A scientific law is liable at anytime to need ______, that is an eternal truth.

单选题The verb "tell" in the sentence "I could tell that he was shy" (Paragraph 3) means ______

单选题It is A(estimated) that a scientific principle has B(a life expectancy) of approximately C(a decade) before D(it drastically) revised or replaced by newer information.

单选题It would be more effective to persuade the teenager smokers to give up smoking if ______.

单选题If you are a fan of science fiction, you've no doubt encountered the term nanotechnology. Yet over the past year also, a series of breakthroughs have transformed nanotech from sci-fi fantasy into a real world. Applied science, in the process, inspired huge investments by business, academia, and government. In industries as diverse as health care, computers, chemicals, and aerospace, nanotech is overhauling production techniques, resulting in new and improved products, some of which may already be in your home or workplace. The inspiration for nanotech goes back to a 1959 speech by the late physicist Richard Feynman, then a professor at the California Institute of Technology, titled "There's Plenty of Room at the Bottom. " Four decades later, Chad Mirkin, a Chemistry professor at Northwestern University's $ 34 million nanotech center, used a nanoscale device to etch most of Feynman's speech onto a surface the size of about 10 tobacco smoke particles. What accounts for the sudden acceleration of nanotechnology? A key breakthrough came in 1990, when researchers at IBM's Almaden Research Center succeeded in rearranging individual atoms at will. Using a device known as a scanning probe microscope, the warn slowly moved 35 atoms to spell the three-letter IBM logo, thus proving Feynman right. The entire Logo was less than three nanometers. Soon, scientists were not only manipulating individual atoms but "spray painting" with them as well. Using a tool known as a molecular beam epitary, scientists have learned to create ultra fine films of specialized crystals, built up one molecular layer at a time. This is the technology used today to build read-head components for computer hard drives. The next stage in the development of nanotechnology borrows a page from noture. Building a supercomputer no bigger than a speck of dust might seem an impossible task, until one realizes that evolution solved such problems more than a billion years ago. Living cells contain all sorts of anisole motors made of proteins that perform myriad mechanical and chemical functions, from muscle contraction to photosynthesis. In some instances, such motors may be re-engineered, or imitated, to produce products and processes useful to humans. How are these biologically inspired machines constructed? Often, they construct themselves, manifesting a phenomenon of nature known as self assembly. The macromolecules of such biological machines have exactly the right shape and chemical binding preferences to ensure that when they combine they will snap together in predesigned ways. For example, the two strands that make up DNA's double helix match each other exactly, which means that if they are separated in a complex chemical mixture, they are still able to find each other easily.

单选题The wreckage of the exploded car ______ the traffic.

单选题Although most dreams apparently happen ______, dream activity may be provoked by external influences. A. spontaneously B. simultaneously C. homogeneously D. instantaneously

单选题What things in life aye you most desirous ______ attaining? A. to B. for C. with D. of

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单选题Some 121 countries may be designated "developing", and of this 121, seventeen countries ______ more than four-fifths of energy consumption.

单选题Why are some of us good at math, or writing, while others ______ at art or basketball?(2002年上海交通大学考博试题)

单选题A It can be argued that the problems, even something B as fundamental as the C ever-increased world population, D have been caused by technological advance.

单选题The drunkenness in this area is a(n) ______of the despair felt by the people there.

单选题Living with a roommate ______ constraint on her, she couldn't play her trumpet or have parties late at night. A. imposing B. illustrating C. impressing D. leaving

单选题______ a declining birth rate, there will be an over-supply of 27, 000 primary school places by 2010, ______ leaving 35 schools idle.

单选题My friend's parents ______ her to marry the poor young man, but at last she succeeded.

单选题 With its graceful movements and salubrious effects on health, Tai Chi has a strong ______ to a vast multitude of people.

单选题In some countries where racial prejudice is acute, violence has so come to be taken for granted as a means of solving differences, that it is not even questioned. There are countries where the white man imposes his rule by brute force; there are countries where the black man protests by setting fire to cities and by looting and pillaging. Important people on both sides who would in other respects appear to be reasonable men, get up and calmly argue in favor of violence—as if it were a legitimate solution, like any other. What is really frightening, what really fills you with despair, is the realization that when it comes to the crunch, we have made no actual progress at all. We may wear collars and ties instead of war-paint, but our instincts remain basically unchanged. The whole of the recorded history of the human race, that tedious documentation of violence, has taught us absolutely nothing. We have still not learnt that violence never solves a problem but makes it more acute. The sheer horror, the bloodshed and the suffering mean nothing. No solution ever comes to light the morning after when we dismally contemplate the smoking ruins and wonder what hit us. The truly reasonable men who know where the solutions lie are finding it harder and harder to get a hearing. They are despised, mistrusted and even persecuted by their own kind because they advocate such apparently outrageous things as law enforcement. If half the energy that goes into violent acts were put to good use, if our efforts were directed at cleaning up the slums and ghettos, at improving living-standards and providing education and employment for all, we would have gone a long way to arriving at a solution. Our strength is undermined by having to mop up the mess that violence leaves in its wake. In a well-directed effort, it would not be impossible to fulfill the ideals of a stable social program. The benefits that can be derived from constructive solutions are everywhere apparent in the world around us. Genuine and lasting solutions are always possible, providing we work within the framework of the law. Before we can even begin to contemplate peaceful co-existence between the races, we must appreciate each other"s problems. And to do this, we must learn about them: it is a simple exercise in communication, in exchanging information. "Talk, talk, talk," the advocates of violence say, "all you ever do is talk, and we are none the wiser." It"s rather like the story of the famous barrister who painstakingly explained his case to the judge. After listening to a lengthy argument the judge complained that after all this talk, he was none the wiser. "Possible, my lord," the barrister replied, "none the wiser, but surely far better informed." Knowledge is the necessary prerequisite to wisdom; the knowledge that violence creates the evils it pretends to solve.