2014年5月托福考试模拟试题及答案(第五套)_第11页

　Question 11-20

　　Molting is one of the most involved processes of a bird’s annual life cycle.

　　Notwithstanding preening and constant care, the marvelously intricate structure of a bird’s

　　Feather inevitably wears out. All adult birds molt their feathers at least once a year, and

　　Line upon close observation, one can recognize the frayed, ragged appearance of feathers that

　　5) are nearing the end of their useful life. Two distinct processes are involved in molting.

　　The first step is when the old, worn feather is dropped, or shed. The second is when a new

　　feather grows in its place. When each feather has been shed and replaced, then the molt

　　can be said to be complete. This, however, is an abstraction that often does not happen:

　　incomplete, overlapping, and arrested molts are quite common.

　　10) Molt requires that a bird find and process enough protein to rebuild approximately

　　one-third of its body weight. It is not surprising that a bird in heavy molt often seems

　　listless and unwell. But far from being random, molt is controlled by strong evolutionary

　　forces that have established an optimal time and duration. Generally, molt occurs at the

　　time of least stress on the bird. Many songbirds, for instance, molt in late summer, when

　　15) the hard work of breeding is done but the weather is still warm and food still plentiful.

　　This is why the woods in late summer often seem so quiet, when compared with the

　　Exuberant choruses of spring.

　　Molt of the flight feathers is the most highly organized part of the process. Some species,

　　for example, begin by dropping the outermost primary feathers on each side (to retain

　　20) balance in the air) and wait until the replacement feathers are about one-third grown before

　　shedding the next outermost, and so on. Others always start with the innermost primary

　　feathers and work outward. Yet other species begin in the middle and work outward on both

　　weeks while the replacement feathers grow.

　　11.The passage mainly discusses how

　　(A) birds prepare for breeding

　　(B) bird feathers differ from species

　　(C) birds shed and replace their feathers

　　(D) birds are affected by seasonal changes

　　12.The word “Notwithstanding” in line 2 is closest　in meaning to

　　(A) despite

　　(B) because of

　　(C) instead of

　　(D) regarding

　　13.The word “intricate” in line 2 is closest in　meaning to

　　(A) regular

　　(B) complex

　　(C) interesting

　　(D) important

　　14.The word “random” in line 12 is closest in　meaning to

　　(A) unfortunate

　　(B) unusual

　　(C) unobservable

　　(D) unpredictable

　　15.The word “optimal” in line 13 is closest in　meaning to

　　(A) slow

　　(B) frequent

　　(C) best

　　(D) early

　　16.Which of the following is NOT mentioned as a　reason that songbirds molt in the late　summer?

　　(A) Fewer predators are in the woods.

　　(B) The weathers is still warm.

　　(C) The songbirds have finished breeding.

　　(D) Food is still available.

　　17. Some birds that are molting maintain balance

　　during flight by

　　(A) constantly preening and caring for their

　　remaining feathers

　　(B) dropping flight feathers on both sides at the

　　same time

　　(C) adjusting the angle of their flight to

　　compensate for lost feathers

　　(D) only losing one-third of their feathers

　　18.The word “Others” in line 21 refers to

　　(A) ducks

　　(B) sides

　　(C) species

　　(D) flight feathers

　　19.The author discusses ducks in order to provide

　　an example of birds that

　　(A) grow replacement feathers that are very long

　　(B) shed all their wing feathers at one time

　　(C) keep their innermost feathers

　　(D) shed their outermost feathers first

　　20. It can inferred from the discussion about ducks

　　that the molting of their flight feathers takes.

　　(A) a year

　　(B) a season

　　(C) several months

　　(D) a few weeks