A ploy can be hollow.Logical formLearned from2 sentences. Pledges of humanitarian relief can be hollow.Logical formLearned from2 sentences. A revenge can be hollow.Logical formLearned from2 sentences. A conversion can be hollow.Logical formLearned from2 sentences. A hollow tree can be in a backyard.Logical formLearned from2 sentences. A boulder can be hollow.Logical formLearned from2 sentences. Denials may remain hollow.Logical formLearned from2 sentences. (Rubber balls) can be hollow.Logical formLearned from2 sentences. A civilization can be hollow.Logical formLearned from2 sentences. Ideals may ring hollow.Logical formLearned from2 sentences. A falsetto can be hollow.Logical formLearned from2 sentences. Words may be ringed hollow.Logical formLearned from2 sentences. A lumber can be hollow.Logical formLearned from2 sentences. A (steel structure) can be hollow.Logical formLearned from2 sentences. A (coffee cup) can be hollow.Logical formLearned from2 sentences.