IV. Reading Comprehension
Questions 38-42
Birds, like mammals, have a four-chambered heart that separates oxygenated and deoxygenated blood. The blood
temperature of birds is from 2˚ to 14˚ higher than that of other mammals. Though the use of the phrase “bird-brain” as an insult
would suggest otherwise, birds in fact have a relatively large brain. They also possess keen sight and acute hearing, though they
have little sense of smell. Birds are highly adapted for flight; their body structures combine lightness and strength. Body weight
is 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 in
other parts of the body. Compactness and firmness are achieved by the fusion of bones in the pelvic region and in other parts of
the skeleton. The heavier parts of bird bodies – the gizzard, intestines, flight muscles, and thigh muscles – are all strategically
located for maintaining balance in flight. Feathers, despite their lightness, are highly protective against cold and wet. Feathers
used for flight, especially, have great strength. Some birds, such as the ostrich, the penguin, and the chicken, lack the power of
flight and have a flat sternum or breastbone, without the prominent keel to which the well-developed flight muscles of other
birds are attached.
In the majority of species of bird there are differences between males and females in plumage coloring. Male birds are
usually the more brilliant or the more distinctly marked and are the aggressors in courtship. Most birds build a nest in which to
lay their eggs. Some birds, such as the oriole, weave an intricate structure, while others lay their eggs directly on the ground
among a few seemingly carelessly assembled twigs. Eggs vary in size, number, color, and shape. In spring and fall many birds
migrate. Not all of the factors motivating this behavior are fully understood. These trips often involve flights of hundreds and
even thousands of miles over mountains and oceans.
【題組】40. Which of the following is NOT mentioned as a reason why birds are able to fly?
(A) Their bones are hollow.
(B) They have hard beaks instead of jaws.
(C) They have flat breastbones.
(D) Their feathers are light.
寫作批改
VIP與詳解卡管理
私人筆記( 0 )
