Sisters can be hollow.Logical formLearned from6 sentences. A straw can be hollow.Logical formLearned from6 sentences. A pledge of a new era of respect may ring hollow.Logical formLearned from6 sentences. A vow may ring hollow.Logical formLearned from6 sentences. Efforts may ring hollow.Logical formLearned from6 sentences. A ceremony may ring hollow.Logical formLearned from6 sentences. A skeleton can be hollow.Logical formLearned from6 sentences. Reminders can be hollow.Logical formLearned from6 sentences. A victory may ring hollow.Logical formLearned from6 sentences. A warning can be hollow.Logical formLearned from6 sentences. Statements may ring hollow.Logical formLearned from6 sentences. A number can be hollow.Logical formLearned from5 sentences. Loaves may sound hollow.Logical formLearned from5 sentences. (Tree stumps) can be hollow.Logical formLearned from5 sentences. A twang can be hollow.Logical formLearned from5 sentences.