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- Eternity, so to speak
- Massive time periods
- Life spans of suns
- Open-front jackets
- Astronomical spans
- They go to great lengths
- Really long times
- Scholars' collars
- Practical eternity
- Immeasurable spans
- Periods of two or more of 40-Across
- Immensely long stretches
- Billion-year time divisions
- Gorges are carved over them
- Many, many, many, many, many moons