sk

Initial position(首):sky, ski, skip, skid, skit, skin, skim, skimp, skill, skillet, sketch, skeleton, skeptical, skate, skirt, skunk, skulk, skull, skew

Final position(尾):ask, bask, cask, task, mask, flask, desk, disk, brisk, frisk, risk, asterisk, whisk, dusk, husk, musk, tusk, kiosk