th

Soft /th/ sound (voiceless)
• Initial position(首):thank, thaw, thwart, therapy, theft, thief, three, theme, theater, theory, thesaurus, thick, think, thin, thing, thimble, thigh, third, thirteen, thirty, thirsty, Thursday, thermal, thermos, thermostat, thermometer, thorough, thorn, thought, thousand, thud, thug, thunder, thumb, thump
• Medial position(中):author, authority, authentic, athlete, anthem, method, nothing, something, anything, filthy, sympathy, telepathy, empathy, empathize, enthusiasm, marathon, mathematics, arithmetic, synthetic, aesthetic, southeast, northwest, ethic, ethnic, strengthen, parentheses, birthday, bathroom, bathtub, pathetic, ethal, lethal, ruthless, panther, orthodox, stethoscope
• Final position(尾):bath, path, math, aftermath, labyrinth, faith, with, width, filth, myth, length, depth, strength, fourth, fifth, sixth, seventh, eighth, ninth, tenth, broth, cloth, moth, month, mammoth, both, oath, growth, south, mouth, booth, tooth, teeth, heath, breath, death, health, wealth, stealth, north, forth, worth, berth, birth, girth, earth, dearth, Ruth, truth, youth, wrath, wreath, beneath, underneath, warmth, swath

Hard /th/ sound (voiced)
• Initial position(首):the, this, that, these, those, there, their, they, them, then, than, thus, though
• Medial position(中):brother, bother, other, mother, father, farther, gather, together, feather, whether, wither, within, rhythm, breathe, soothe