A (desperation effort) may sound hollow.Logical formLearned from1 sentences. A (lie campaign) may ring hollow.Logical formLearned from1 sentences. Explanations can be hollow.Logical formLearned from1 sentences. Explanations may sound hollow.Logical formLearned from1 sentences. A distancing can be hollow.Logical formLearned from1 sentences. An album may ring hollow.Logical formLearned from1 sentences. A book may ring hollow.Logical formLearned from1 sentences. Gains may prove hollow.Logical formLearned from1 sentences. A center of a flowerhead can be hollow.Logical formLearned from1 sentences. A (metal disk) can be hollow.Logical formLearned from1 sentences. An expansion can be hollow.Logical formLearned from1 sentences. A den can be high in a hollow tree.Logical formLearned from1 sentences. (Plant stalks) can be hollow.Logical formLearned from1 sentences. A (crystal sphere) can be hollow.Logical formLearned from1 sentences. (Vacuum chambers) can be hollow.Logical formLearned from1 sentences.