A thunder can be hollow.Logical formLearned from9 sentences. Arms can be hollow.Logical formLearned from9 sentences. A message can be hollow.Logical formLearned from9 sentences. A loaf may sound hollow.Logical formLearned from9 sentences. A pang can be hollow.Logical formLearned from9 sentences. A defense can be hollow.Logical formLearned from9 sentences. A celebrity can be hollow.Logical formLearned from9 sentences. A pocket can be hollow.Logical formLearned from9 sentences. Speeches can be hollow.Logical formLearned from9 sentences. Some trees can be hollow.Logical formLearned from9 sentences. A resonance can be hollow.Logical formLearned from9 sentences. Reassurance can be hollow.Logical formLearned from9 sentences. Columns can be hollow.Logical formLearned from9 sentences. An echo can be hollow.Logical formLearned from9 sentences. (Metal drums) can be hollow.Logical formLearned from9 sentences.