A (coal mine explosion) may kill some persons.Logical formLearned from20 sentences. A (coal mine) may collapse.Logical formLearned from20 sentences. Investment can be in (coal mining).Logical formLearned from19 sentences. A (coal dust) can be combustible.Logical formLearned from19 sentences. Layers can be constituted-of-or-filled-with coal.Logical formLearned from19 sentences. Coal may undergo a shipping.Logical formLearned from19 sentences. (Coal fields) may pertain-to a country.Logical formLearned from19 sentences. A (cast coal mine) can be open.Logical formLearned from19 sentences. (Coal mines) may be closed.Logical formLearned from19 sentences. A search can be for coal.Logical formLearned from19 sentences. Coal may be transported.Logical formLearned from19 sentences. A combination can be constituted-of-or-filled-with coal.Logical formLearned from19 sentences. A coal can be pulverised.Logical formLearned from19 sentences. (Coal fires) can be underground.Logical formLearned from19 sentences. Coal can be for fuel.Logical formLearned from19 sentences.