An obstacle can be to peace.Logical formLearned from1 705 sentences. Obstacles can be serious.Logical formLearned from1 495 sentences. An obstacle can be serious.Logical formLearned from1 268 sentences. Obstacles can be formidable.Logical formLearned from830 sentences. Obstacles can be insurmountable.Logical formLearned from687 sentences. An obstacle can be insurmountable.Logical formLearned from668 sentences. An obstacle can be to peace.Logical formLearned from597 sentences. An obstacle can be formidable.Logical formLearned from556 sentences. Obstacles can be regulatory.Logical formLearned from389 sentences. Obstacles can be physical.Logical formLearned from386 sentences. An obstacle can be that something-is-the-case.Logical formLearned from370 sentences. A series can be constituted-of-or-filled-with obstacles.Logical formLearned from361 sentences. An obstacle may pertain-to a person.Logical formLearned from355 sentences. An obstacle may pertain-to a male.Logical formLearned from323 sentences. Obstacles can be to peace.Logical formLearned from323 sentences.