試題詳解

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.