問題詳情

IV. Reading ComprehensionQuestions 38-42Birds, like mammals, have a four-chambered heart that separates oxygenated and deoxygenated blood. The bloodtemperature of birds is from 2˚ to 14˚ higher than that of other mammals. Though the use of the phrase “bird-brain” as an insultwould suggest otherwise, birds in fact have a relatively large brain. They also possess keen sight and acute hearing, though theyhave little sense of smell. Birds are highly adapted for flight; their body structures combine lightness and strength. Body weightis reduced by the presence of a horny bill instead of heavy jaws and teeth and by air sacs in their hollow bones as well as inother parts of the body. Compactness and firmness are achieved by the fusion of bones in the pelvic region and in other parts ofthe skeleton. The heavier parts of bird bodies – the gizzard, intestines, flight muscles, and thigh muscles – are all strategicallylocated for maintaining balance in flight. Feathers, despite their lightness, are highly protective against cold and wet. Feathersused for flight, especially, have great strength. Some birds, such as the ostrich, the penguin, and the chicken, lack the power offlight and have a flat sternum or breastbone, without the prominent keel to which the well-developed flight muscles of otherbirds are attached.In the majority of species of bird there are differences between males and females in plumage coloring. Male birds areusually the more brilliant or the more distinctly marked and are the aggressors in courtship. Most birds build a nest in which tolay their eggs. Some birds, such as the oriole, weave an intricate structure, while others lay their eggs directly on the groundamong a few seemingly carelessly assembled twigs. Eggs vary in size, number, color, and shape. In spring and fall many birdsmigrate. Not all of the factors motivating this behavior are fully understood. These trips often involve flights of hundreds andeven thousands of miles over mountains and oceans.
38. What is the writer’s primary purpose?
(A) To point out the differences between birds and mammals.
(B) To provide information about birds.
(C) To explain bird mating rituals.
(D) To offer advice to bird watchers.

參考答案

答案：B
難度：簡單0.818182
統計：A(7),B(45),C(0),D(2),E(0)

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