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brain •abstain, appertain, arcane, arraign, ascertain, attain, Bahrain, bane, blain, brain, Braine, Cain, Caine, campaign, cane, chain, champagne, champaign, Champlain, Charmaine, chicane, chow mein, cocaine, Coleraine, Coltrane, complain, constrain, contain, crane, Dane, deign, demesne, demi-mondaine, detain, disdain, domain, domaine, drain, Duane, Dwane, Elaine, entertain, entrain, explain, fain, fane, feign, gain, Germaine, germane, grain, humane, Hussein, inane, Jain, Jane, Jermaine, Kane, La Fontaine, lain, lane, legerdemain, Lorraine, main, Maine, maintain, mane, mise en scène, Montaigne, moraine, mundane, obtain, ordain, pain, Paine, pane, pertain, plain, plane, Port-of-Spain, profane, rain, Raine, refrain, reign, rein, retain, romaine, sane, Seine, Shane, Sinn Fein, skein, slain, Spain, Spillane, sprain, stain, strain, sustain, swain, terrain, thane, train, twain, Ujjain, Ukraine, underlain, urbane, vain, vane, vein, Verlaine, vicereine, wain, wane, Wayne •watch chain • mondaine • Haldane •ultramundane • Cellophane •novocaine • sugar cane •
How about "The rain in Spain stays mainly on the plain".