Isotopes can be constituted-of-or-filled-with berkelium.Logical formLearned from4 sentences. Deuterium can be isotopes of hydrogen.Logical formLearned from4 sentences. A combination can be constituted-of-or-filled-with isotopes.Logical formLearned from4 sentences. (Isotope ratios) may indicate that something-is-the-case.Logical formLearned from4 sentences. Some isotopes can be constituted-of-or-filled-with lead.Logical formLearned from4 sentences. Radioactive isotopes can be unstable.Logical formLearned from4 sentences. Isotopes can be constituted-of-or-filled-with fermium.Logical formLearned from4 sentences. Isotopes can be constituted-of-or-filled-with californium.Logical formLearned from4 sentences. Isotopes can be constituted-of-or-filled-with ytterbium.Logical formLearned from4 sentences. Isotopes can be constituted-of-or-filled-with rutherfordium.Logical formLearned from4 sentences. Isotopes can be constituted-of-or-filled-with indium.Logical formLearned from4 sentences. Isotopes can be constituted-of-or-filled-with krypton.Logical formLearned from4 sentences. A radioactive isotope can be long-lived.Logical formLearned from4 sentences. Fissile isotopes can be in fertile material.Logical formLearned from4 sentences. A nucleus may pertain-to an isotope.Logical formLearned from4 sentences.