otein 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
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