(Fibre membranes) can be hollow.Logical formLearned from7 sentences. A light can be hollow.Logical formLearned from7 sentences. An explanation may ring hollow.Logical formLearned from7 sentences. A pop can be hollow.Logical formLearned from7 sentences. Victories can be hollow.Logical formLearned from7 sentences. A joy can be hollow.Logical formLearned from7 sentences. An organization can be hollow.Logical formLearned from7 sentences. Skin can be hollow.Logical formLearned from7 sentences. Crystals can be hollow.Logical formLearned from7 sentences. A cross can be hollow.Logical formLearned from7 sentences. A success can be hollow.Logical formLearned from7 sentences. A vortex can be hollow.Logical formLearned from7 sentences. A bullet can be hollow.Logical formLearned from7 sentences. Guides can be hollow.Logical formLearned from7 sentences. A gesture can be hollow.Logical formLearned from7 sentences.