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(一)动物学家观察发现:老鹰在树梢和悬崖上筑巢时,先衔一些荆棘放在底层,再叼一些尖锐的石子铺在荆棘上,最后才衔枯草、
(1) The zoologist observed that when the eagle nests on the tops of trees and cliffs, it first holds some thorns on the bottom, and then picks up some sharp stones on the thorns.