A (plastic sphere) can be hollow.Logical formLearned from2 sentences. A variation may produce hollow castings.Logical formLearned from2 sentences. A (fabric wing) can be hollow.Logical formLearned from2 sentences. Flutes can be hollow.Logical formLearned from2 sentences. Inner spaces can be hollow.Logical formLearned from2 sentences. A (cannon ball) can be hollow.Logical formLearned from2 sentences. A (cast iron sphere) can be hollow.Logical formLearned from2 sentences. A rectangular box can be hollow.Logical formLearned from2 sentences. A skirt can be hollow.Logical formLearned from2 sentences. A milieu can be hollow.Logical formLearned from2 sentences. Protuberances can be hollow.Logical formLearned from2 sentences. A cow can be hollow.Logical formLearned from2 sentences. A hollow earth can be concave.Logical formLearned from2 sentences. Acoustic instruments can be hollow.Logical formLearned from2 sentences. A (frequency responsiveness) may pertain-to a hollow body.Logical formLearned from2 sentences.