A figure can be hollow.Logical formLearned from13 sentences. (Glass spheres) can be hollow.Logical formLearned from13 sentences. Tones can be hollow.Logical formLearned from13 sentences. A promise may ring hollow.Logical formLearned from13 sentences. A pursuit can be hollow.Logical formLearned from13 sentences. Peace can be hollow.Logical formLearned from13 sentences. A barrel can be hollow.Logical formLearned from12 sentences. A body can be hollow.Logical formLearned from12 sentences. A brick can be hollow.Logical formLearned from12 sentences. A crown can be hollow.Logical formLearned from12 sentences. An opening can be hollow.Logical formLearned from12 sentences. Bullets can be hollow.Logical formLearned from12 sentences. A nickel can be hollow.Logical formLearned from12 sentences. A cage can be hollow.Logical formLearned from12 sentences. Ships can be hollow.Logical formLearned from12 sentences.