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COOK

book, brook, brooke, chook, cooke, crook, crooke, flook, gook, hook, hooke, look, mook, nook, rook, rooke, schnook, schook, shook, snook, stroock, took, tooke, zook

COOL

boole, boule, bruehl, brule, buehl, buel, buhl, coole, drool, duell, dule, fool, ghoul, hoole, joule, juel, jule, kool, kreul, luelle, muehl, mule, pool, poole, poul, raul, reul, reule, rhule, ruel, rule, school, schuele, spool, sproule, sproull, spruell, spruiell, spruill, stool, tool, toole, tuel, tuell, tuyle, who'll, you'll, yuill, yuille, yule