A (subway tunnel) may undergo a collapse.Logical formLearned from7 sentences. A collapse can be in a century.Logical formLearned from7 sentences. Some stages can be constituted-of-or-filled-with collapse.Logical formLearned from7 sentences. A Spanish empire may undergo a collapse.Logical formLearned from7 sentences. A feudal system may undergo a collapse.Logical formLearned from7 sentences. Icelandic banks may undergo a collapse.Logical formLearned from7 sentences. Caves may undergo a collapse.Logical formLearned from7 sentences. A collapse may pertain-to the world.Logical formLearned from7 sentences. Finances may undergo a collapse.Logical formLearned from7 sentences. A collapse may pertain-to an airline.Logical formLearned from7 sentences. An (investment trust) may undergo a collapse.Logical formLearned from7 sentences. A collapse can be accidental.Logical formLearned from7 sentences. Ussr may undergo a collapse.Logical formLearned from7 sentences. A collapse can be apparent.Logical formLearned from7 sentences. A cause of a collapse may remain unknown.Logical formLearned from7 sentences.