A river may symbolize a greatness of an ancient civilization.Logical formLearned from11 sentences. A civilization may undergo a test.Logical formLearned from11 sentences. A country may be close_offed from a rest of civilization.Logical formLearned from11 sentences. Achievements may pertain-to civilization.Logical formLearned from11 sentences. Institutions may pertain-to civilization.Logical formLearned from11 sentences. A civilization can be underwater.Logical formLearned from11 sentences. Civilizations may undergo cooperation.Logical formLearned from11 sentences. A symbol may suggest civilization.Logical formLearned from11 sentences. A woodpecker may destroy civilization.Logical formLearned from11 sentences. Some aspects can be constituted-of-or-filled-with western civilization.Logical formLearned from11 sentences. A threat can be to American civilization.Logical formLearned from11 sentences. A civilization may invent gunpowder.Logical formLearned from11 sentences. Values can be constituted-of-or-filled-with civilizations.Logical formLearned from11 sentences. Some civilizations may rise.Logical formLearned from11 sentences. A nation can be in a history of civilization.Logical formLearned from11 sentences.