A boom can be hollow.Logical formLearned from20 sentences. Tines can be hollow.Logical formLearned from20 sentences. Vessels can be hollow.Logical formLearned from19 sentences. A tree can be hollow.Logical formLearned from19 sentences. A ritual can be hollow.Logical formLearned from19 sentences. Channels can be hollow.Logical formLearned from19 sentences. An expression can be hollow.Logical formLearned from19 sentences. A truce can be hollow.Logical formLearned from19 sentences. A smile can be hollow.Logical formLearned from19 sentences. An argument can be hollow.Logical formLearned from19 sentences. Lies can be hollow.Logical formLearned from19 sentences. Praise can be hollow.Logical formLearned from19 sentences. Hills can be hollow.Logical formLearned from19 sentences. (Peace promises) may ring hollow.Logical formLearned from19 sentences. A rubber can be hollow.Logical formLearned from18 sentences.