| A: | 18O + 18O16O 18O18O16O | (5) |
| B: | 16O + 18O18O 16O18O18O | (6) |
| S: | 18O + 16O18O 18O16O18O | (7) |
| I: | 16O + 18O18O 18O16O18O | (8) |
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