19. Why does the author use the word luckily in mentioning that the Ambulocetus natans fossil
included hind legs in paragraph 5?
(A)Fossil legs of early whales are a rare find.
(B) The legs provided important information about the evolution of cetaceans.
(C) The discovery allowed scientists to reconstruct a complete skeleton of the whale.
(D)Until that time, only the front legs of early whales had been discovered.
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統計: A(0), B(5), C(0), D(1), E(0) #3293659
統計: A(0), B(5), C(0), D(1), E(0) #3293659