The /u/ vowel is usually spelled <oo>, <ew>, <u> and <o> after <wh> in who'd. The /aɪ/ diphthong is spelled in a number of ways including <iCe>, <ui>, <y>, <uy> in buy, and occurs in the letter names I and Y.
This is a contrast between a long vowel and a diphthong, well separated in the mouth and distinguished by lip-rounding. It is not a problem for any group of learners.
There is one taboo word pair: coon/kine.
Interesting pairs include:
allude allied
elude elide
lunar liner
oodles idles
pollute polite
rueful rifle
unsuited unsighted
The density figure is 5.48%. The set makes 138 semantic contrasts giving a loading of 53.1%.
allude allied bestrewed bestride blew Blyth blue Blyth boo buy booing buying boos buys boo by boo bye boos byes booed bide boon bine boons bines boot bight boots bights boot bite booting biting boots bites brewed bride brewer briar brewers briars brood bride broods brides brute bright buhl bile chewed chide coon kine coot kite coots kites crew cry crewed cried crewing crying crews cries croups cripes cruise cries do Di do die doing dying do's dies do dye do's dyes doer dire doer dyer doers dyers doom dime dooms dimes drew dry elude elide eluded elided eludes elides eluding eliding flew fly flue fly flues flies flute flight fluted flighted flutes flights fluting flighting fool file fooled filed fooling filing fools files fruit fright fruited frighted fruiting frighting fruits frights fruitful frightful fruitfully frightfully fruitfulness frightfulness glued glide gnu nigh goo guy Goole guile groom grime groomed grimed grooming griming grooms grimes group gripe groups gripes Hoo hi hoot height hoots heights hooves hives jewels Giles joules Giles lieu lie loo lie loos lies loofahs lifers loom lime loomed limed looming liming looms limes loon line loons lines loose lice loot light looted lighted looting lighting loots lights looter lighter looters lighters Luke like lunar liner Luton lighten moo my moon mine mooned mined mooning mining moons mines mooned mind moose mice moot might noon nine noose nice oodles idles ooze I's overflew overfly pollute polite polluter politer pooh pi Poole Pyle pool pile pooled piled pooling piling pools piles poop pipe poops pipes Pru pry prude pride prudes prides prude pried rheum rhyme rood ride roods rides roof rife room rhyme roomed rhymed rooming rhyming rooms rhymes root right rooted righted rooting righting roots rights root rite roots rites root write roots writes rooting writing route right routes rights routing righting routed righted route rite routes rites route write routes writes routing writing rude ride ruder rider rue rye rued ride rueful rifle rule rile ruled riled rules riles ruling riling rune Rhine shoe shy shoeing shying shoes shies shoo shy shooed shied shoos shies shooing shying slew sly slewed slide sluice slice sluiced sliced sluices slices sluicing slicing snood snide snoop snipe snooped sniped snooping sniping snoops snipes snooper sniper snoopers snipers soon sign soothe scythe soothed scythed soothes scythes sou sigh sous sighs spook spike spooks spikes spooky spiky spookier spikier spookiest spikiest spoon spine spoons spines stool stile stools stiles stool style stools styles strewed stride suit cite suits cites suited cited suiting citing suit sight suits sights suited sighted suiting sighting suit site suits sites suited sited suiting siting swoon swine swoop swipe swooped swiped swooping swiping swoops swipes tomb thyme tombs times too tie two tie twos ties tool tile tooled tiled tooling tiling tools tiles toot tight toots tights tootle title tootled titled tootles titles trews tries troop tripe truce trice truces trices true try trued tried truing trying truer trier unsuited unsighted who'd hide who're higher who's hies woo why woo Y woos Y's wooed wide wooer wire wooers wires woof wife wound whined wound wind wounding winding wounds winds
John Higgins, Shaftesbury, December 2009