[填空题]Many scientists believed that they could produce an anti-AIDS vaccine that could be given to people to ______the disease.

[填空题]Many scientists believed that they could produce an anti-AIDS vaccine that could be given to people to ______the disease.

[简答题]Observational Learning
Some scientists believed that direct reinforcement could not account for all types of learning. Bandura’s learning theory added a social element, arguing that people can learn new information and behaviors by watching other people. Known as observational learning (or modeling), this type of learning can be used to explain a wide variety of behaviors. Observational learning takes place when an individual acquires a habit or skill through witnessing the performance of another person. Such learning often, but not always, involves imitation of the observed activities.
Question: The professor uses an experiment to illustrate the definition of "observational learning". Explain how this example is related to the reading passage.

[填空题]Scientists believed that Mayan city ______ because many buildings were left unfinished.

[单项选择]Scientists have discovered that many animals seem to be highly _________ to various signals associated with earthquakes.
A. sensible
B. sensual
C. sentimental
D. sensitive

[填空题]What do scientists think of dreams
Many scientists believe that dreams are （）.

[单项选择]Scientists now believe that many, if not all, living things are born with some type of hidden clock. These clocks are sometimes set by the number of hours of light or darkness in a day, by the rhythm of the tides or by the seasons. One of the most remarkable of nature’s living clocks belongs to the fiddler crab, that familiar beach-dweller with the overgrown claw. Biologists have long known that the crab’s shell is darkest during the day, grows pale in late afternoon, then begins to darken again at daybreak. This daytime darkening is valuable for protection against enemies and sunlight, and for many years it was thought to be a simple response by the crab to the sun--just as if we were to get a tan during the day and lose it at night. But when an enterprising scientist placed a fiddler crab in darkness, he was amazed to find that the color of the crab’s shell kept ticking off the time with the same accuracy. Yet another startling fact was revealed: the crab’s shell re
A. the fiddler crab’s shell reached the darkest color at the same time in Cape Cod, Massachusetts and its neighboring island
B. the fiddler crab continued to change color in the dark
C. plants will not grow without sunlight
D. all of the above

[单项选择]Scientists have long believed that constructing memories is like playing with neurological toys. Exposed to a barrage of sensations from the outside world, we connect together brain cells to form new patterns of electrical connections that stand for images, smells, touches and sounds.
The most unshakable part of this belief is that the neurons used to build these memory circuits are depletable resource, like petroleum or gold. We are each given a finite number of cells, and the supply gets smaller each year. That is certainly how it feels as memories blur with middle age and it gets harder and harder to learn new things. Maybe it’s time for this notion to be forgotten-or at least radically revised.
In the past two years, a series of confusing experiments has forced scientific researchers to rethink this and other assumptions about how memory works. The perplexing results of these experiments remind scientists how much they have to learn about one of the last great mysteries-h
A. The neurons used to build the memory are a depletable resource.
B. The reason of memory loss as one grows older is that the neurons are worn out with the increase of age.
C. New memories do not need the supply of new neurons in the brain.
D. All of above.

[填空题]Up until now, scientists still could not explain how leaves will change colors during the fall.

[单项选择]That Louise Nevelson is believed by many critics to be the greatest twentieth-century sculptor is all the more remarkable because the greatest resistance to women artists has been, until recently, in the field of sculpture. Since Neolithic times, sculpture has been considered the prerogative of men, partly, perhaps, for purely physical reasons: it was erroneously assumed that women were not suited for the hard manual labor required in sculpting stone, carving wood, or working in metal. It has been only during the twentieth century that women sculptors have been recognized as major artists, and it has been in the United States, especially since the decades of the fifties and sixties, that women sculptors have shown the greatest originality and creative power. Their rise to prominence parallels the development of sculpture itself in the United States: while there had been a few talented sculptors in the United States before the 1940’s, it was only after 1945 — when New York was rapidly b
A. realism in Nevelson’ work.
B. the unique qualities of Nevelson’ work.
C. the extent of critical approval of Nevelson’ work.
D. a distinction between sculpture and painting.