En este siglo la medicina _____ mucho.
A、se ha avanzado
B、ha avanzado
C、se avanzó
D、había avanzado
A、se ha avanzado
B、ha avanzado
C、se avanzó
D、había avanzado
第1题
A.Because he wanted to prove the importance of a thorough feasibility investigation before taking any of the recommended options.
B.Because the main problem in Central and South American markets is poor health conditions.
C.Because he wanted to arrange another longer visit to Brazil or Chile early next year.
第2题
A.By using their body to pave the way for others.
B.By covering holes inside their nest.
C.By determining which one is the best fit.
D.By stepping on remainder's back.
第3题
A . Management reserve, unplanned allowance fund.
B . Management reserve, contingency.
C . Contingency fund, management reserve.
D . Unplanned allowance fund, budgetary reserve.
E . Unplanned reserve, planned reserve.
第4题
activities provide evidence of their evolution. Clues to this evolutionary process can be
found in the activities of play and in the behavior. and movements of birds during mating,
Line such as incessant pulling at strips of vegetation or scraping of the soil. During the early
(5) days of the reproductive cycle, the birds seem only to play with the building materials. In
preparation for mating, they engage in activities that resemble nest-building, and continue
these activities throughout and even after the mating cycle. Effective attempts at construction
occur only after mating.
Although nest-building is an instinctive ability, there is considerable adaptability in
(10)both site selection and use of materials, especially with those species which build quite
elaborate constructions. Furthermore, some element of learning is often evident since
younger birds do not build as well as their practiced elders. Young ravens, for example,
first attempt to build with sticks of quite unsuitable size, while a jackdaw's first nest
includes virtually any movable object. The novelist John Steinbeck recorded the contents
(15)of a young osprey nest built in his garden, which included three shirts, a bath towel, and
one arrow.
Birds also display remarkable behavior. in collecting building materials. Crows have
been seen to tear off stout green twigs, and sparrowhawks will dive purposefully onto a
branch until it snaps and then hang upside down to break it off. Golden eagles, over
(20)generations of work, construct enormous nests. One of these, examined after it had been
dislodged by high winds, weighed almost two tons and included foundation branches
almost two meters long. The carrying capacity of the eagles, however, is only relative to
their size ant1 most birds are able to carry an extra load of just over twenty percent of their
body weight.
The word "obscure" in line 1 is closest in meaning to
A.interesting
B.unclear
C.imperfect
D.complex
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