A challenge may pertain-to an unknown.Logical formLearned from11 sentences. An unknown can be in a (jewelry industry).Logical formLearned from11 sentences. An unknown can be around parts.Logical formLearned from11 sentences. A businessman can be an unknown.Logical formLearned from11 sentences. Millions can be constituted-of-or-filled-with unknowns.Logical formLearned from11 sentences. Some actors can be unknowns.Logical formLearned from11 sentences. A (faith journey) can be into an unknown.Logical formLearned from11 sentences. An unknown can be in an equation.Logical formLearned from11 sentences. Death can be an unknown.Logical formLearned from11 sentences. A (whereabouts unknown) may pertain-to a male.Logical formLearned from11 sentences. A person may have a fear of an unknown.Logical formLearned from11 sentences. Some equations can be with some unknowns.Logical formLearned from11 sentences. A person may remain an unknown.Logical formLearned from11 sentences. An unknown may threaten recovery.Logical formLearned from11 sentences. An unknown can be from a country.Logical formLearned from11 sentences.