An incident may prove a (turning point).Logical formLearned from5 sentences. Persons may prove a truth.Logical formLearned from5 sentences. An approach may prove unworkable.Logical formLearned from5 sentences. An impact may prove that something-is-the-case.Logical formLearned from5 sentences. Cooperation may prove fruitful.Logical formLearned from5 sentences. Exercises may prove that something-is-the-case.Logical formLearned from5 sentences. A system may prove workable.Logical formLearned from5 sentences. A search may prove elusive.Logical formLearned from5 sentences. A court may prove a case.Logical formLearned from5 sentences. A search may prove negative.Logical formLearned from5 sentences. Examinations may prove that something-is-the-case.Logical formLearned from5 sentences. Experience of some years may prove that something-is-the-case.Logical formLearned from5 sentences. A course of history may prove that something-is-the-case.Logical formLearned from5 sentences. Negotiations may prove that something-is-the-case.Logical formLearned from5 sentences. A change may prove that something-is-the-case.Logical formLearned from5 sentences.