UPGRADABILITY

aa ab ad ag ai al ar at ay ba bi by id it la li pa pi ta ti up ut ya

aal aba aby aga aid ail air ait ala alb alp alt apt arb art baa bad bag bal bap bar bat bay bid big bit bra bud bug bur but buy dab dag dal dap day dib dig dip dit dry dub dug dui dup gab gad gal gap gar gat gay gib gid gip git gul gut guy gyp lab lad lag lap lar lat lay lib lid lip lit lug pad pal par pat pay pia pig pit piu ply pry pub pud pug pul pur put pya rad rag rai rap rat ray ria rib rid rig rip rub rug rut rya tab tad tag tap tar tau til tip try tub tug tui tup urb urd urp uta yag yap yar yid yip yup

ably abri abut adit agar agly airt airy alar alba alga alit aria arid aril arty aryl atap auld aura baal bail bait bald bard baud bidi bird birl blat blip blur brad brag brat bray brig brit brut bura burd burg burl burp bury byrl darb dart data daub daut dial dipt dirl dirt dita drab drag drat dray drib drip drub drug dual duit duly dura duty gaby gadi gait gala gapy garb gaud gaur gild gilt gird girl girt glad glia glib glut grab grad grat gray grid grip grit grub guar guid gulp gyri idly idyl iglu ilia irid lady laid lair lard lari lati latu laud liar lipa lira liri litu padi paid pail pair paly para pard part paty pial pili pily pita pity plat play plug prat prau pray prig ptui pula puli puri purl raga ragi raia raid rail rapt raya rial ruby ruga ruly tabu tail tala tali tapa tarp tidy tipi tirl trad trap tray trig trip trug tuba turd ugly upby yagi yald yard yaud yaup yird yuga yurt