rarefaction

n. 变成稀薄,稀薄化,稀薄

rapid transit, rapid-fire, rapidity, rapidly, rapids, rapier, rapier-thrust, rapine, rapist, rapport, rapprochement, rapscallion, rapt, raptly, rapture, rapturous, rapturously, rare, rare earth, rarebit, rarefied, rarefy, rarely, rareness, raring, rarity, rascal, rascally, rase, rash, rasher, rashly, rashness, rasp, raspberry, raspy, Rastafarian, rat, rat-a-tat-tat, rat-tat,