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47.According to the passage,when did Herakleion and Eastern Canopus disappear? 7 `& z" }/ b1 h% v! o, a 48.As Stanley said,if you want to know how,when or why Herakleion and Eastern Canopus disappeared,there was/were____________to refer to. # a. n e+ Z; N. O( a
49.Stanley thought that_________was to blame for the cities’collapse in the middle of the eighth century A.D. 外语学习网6 C' b6 o: f. e$ j
50.What found below the waters could show that the cities were once the destinations for religious pilgrims? ! v- X7 K2 R% j# E/ d+ w 51.According to the author,the fortunes of Herakleion and Eastern Canopus declined in__________________.