A (fiber membrane material) can be hollow.Logical formLearned from2 sentences. (Box girder bridges) can be hollow.Logical formLearned from2 sentences. (Cheek bones) can be hollow.Logical formLearned from2 sentences. A ritualism can be hollow.Logical formLearned from2 sentences. A nanocrystal can be hollow.Logical formLearned from2 sentences. An absorber can be hollow.Logical formLearned from2 sentences. (Fiber filters) can be hollow.Logical formLearned from2 sentences. (Lava tubes) can be hollow.Logical formLearned from2 sentences. Some concretions can be hollow.Logical formLearned from2 sentences. (Drive shafts) can be hollow.Logical formLearned from2 sentences. A flow can be hollow.Logical formLearned from2 sentences. A (tile block) can be hollow.Logical formLearned from2 sentences. A cove can be hollow.Logical formLearned from2 sentences. A hooray can be hollow.Logical formLearned from2 sentences. A drift can be hollow.Logical formLearned from2 sentences.