A parent may contribute.Logical formLearned from8 sentences. The atmosphere may contribute to global warming.Logical formLearned from8 sentences. Persons may contribute to a system.Logical formLearned from8 sentences. (Sulfur dioxide) may contribute to (acid rain).Logical formLearned from8 sentences. Sources may contribute to a packet.Logical formLearned from8 sentences. Defects may contribute to an accident.Logical formLearned from8 sentences. A use may contribute to a defense.Logical formLearned from8 sentences. Factors may contribute to changes.Logical formLearned from8 sentences. Sectors may contribute.Logical formLearned from8 sentences. (Greenhouse emissions) may contribute to global warming.Logical formLearned from8 sentences. A person may contribute to teaching.Logical formLearned from8 sentences. Participation may contribute to an education of students.Logical formLearned from8 sentences. A paper may contribute.Logical formLearned from8 sentences. Factors may contribute to failure.Logical formLearned from8 sentences. Work may contribute to knowledge.Logical formLearned from8 sentences.