Plateaus are often referred to as tablelands （ ）essentially flat topped and stand conspicuously above an adjacent land area.
A.because are B.because they are C.because of their D.which because they are
相关问题推荐
The importance of protecting rainforests from human invasion is increasingly realized by developing and developed countries（ ）.
A.both B.either C.alike D.apart
DDT, the most powerful pesticide the world has ever known, exposed nature's vulnerability. Unlike mostApesticides, whose effectiveness is limited to destroy one or two types of insects, DDT is capable of killing hundreds of different kinds at once.BC D
A.has ever known B.whose effectiveness is C.limited to destroy D.is capable of killing
The novel will be read a long lime for its minute and almost uncanny insight into army life, its（ ）dialogue, its sheer narrative pull, its portrayal of the tenderness that sometimes is found beneath the crudest animal drives, its absence of mock heroics, its comic absurdities and irony and, above, all else, its revelation of the perver¬sity of human nature in the face of evil.
A.pungent B.notorious C.anticlimactic D.shaky
The human criterion for perfect vision is 20/20 for reading the standard lines on a Snellen eye chart without a hitch. The score is determined by how well you read lines of letters of different sizes from 20 feet away. But being able to read the bottom line on the eye chart does not approximate perfection as far as other species are concerned. Most birds would consider us very visually handicapped. The hawk, for instance, has such sharp eyes that it can spot a dime ea the side walk while perched on the top of the Empire State Building. It can make fine visual distinctions because it is blessed with one million cones per square millimeter in its retina. And in water, humans are far-sighted, while the kingfisher, swooping down to spear fish, can see well in both air and water because it is endowed with two foveae -areas of the eye, consisting mostly of cones, that provide visual distinctions. One foveae permits the bird, while in the air to scan the water below with one eye at a time. This is called monocular vision. Once it hits the water, the other fovea joins in, allowing the kingfisher to focus bath eye, like binoculars, on it prey at the same time. A frogs vision is distinguished by its ability to perceive things as a constant motion picture. Known as "bug detectors", a highly developed set of cells in a frog's eyes responds mainly to moving objects. So, it is said that a frog sitting in a field of dead bugs wouldn’t see them as food and would starve.The bee has a “compound ’’eye, which is used for navigation. It has 15,000 facet, that divide what it seen into a pattern of dots, or mosaic. With this kind of vision, the bee sees the sun only as constantly measures the angle of its line of fight in relation to the sun. A bee's' eye also gauges flight speed. And if that is not enough to leave our 20/20 “perfect vision, paling into insignificance, the bee is capable of seeing something we can't-ultraviolet light. Thus, what humans consider to be "perfect vision" is in fact rather limited when we look at other species. However, there is still much to be said for the human eye. Of all the mammals, only humans and some primates can enjoy the pleasure of color vision.1.What does the passage mainly discuss?2.According to the passage, why might birds and animals consider humans very visually handicapped?3.According to the passage, which of the following is NOT true?4.The word "that” in line 10 refer to （ ）.5.Which of the following can be inferred from the passage?
A.Eye variation among different species B.Limits of the human eye C.Perfect vision D.Different eyes for different uses
问题2：
A.Humans can't see very well in either air or water. B.Humans eyes are not as well suited to our needs. C.The main outstanding feature of human eyes is color vision. D.Huma
Darwin stated that the more survival characteristics a creature has （ ）the chance that new species will adopt these characteristics.
A.the best B.the better C.better than D.as good as
