- - They seldom mix
- - They don't react well
- - Sergeant is mixing neon and argon
- - Argon and neon, e.g
- - Nonreactive elements, and what are hidden in the answers to 17-, 26-, and 47-Across
- - Helium, neon, argon, etc.
- - sergeant is worried about neon and helium, say
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