spur

n.马刺；激励 vt.鞭策，鼓舞，促进

sprinter, sprite, sprocket, sprout, spruce, sprucely, spruceness, sprung, spry, spryly, spryness, spud, spud-bashing, spume, spun, spun glass, spun silk, spun sugar, spunk, spunky, spurious, spuriously, spuriousness, spurn, spurt, sputnik, sputter, sputum, spy, spy-glass, spyglass, Sq, Sqn Ldr, squab, squabble, squad, squad car, squaddie (also squaddy), squadron, squadron leader,