There are thousands, here are a sampler:
Some Scrabble words that start with U are:upususeunderuncleurineuntoundounclearunnecessaryumbrellaurgentuglyusefulumberutilityunusualunguentuniversalupperundulyundecidedutmostunitunmanageable
Words starting with USHUsherUsheranceUsherancesUsherdomUsherdomsUsheredUsheressesUsheretteUsherettesUsheringUsheringsUsherlessUsherredUsherringUshersUshershipUsherships
knowledge
Axe.
avenue??
effecteffigyefforteffuse
There are no words that start with ZH, here are some words that start with z:ZacatonZaddickZaffarsZaffersZaffirsZaffresZaggingZaikaisZamarraZamarroZananasZandersZaniestZanyishZapateoZappersZappierZappingZaptiahZaptiehZarebasZareebaZaribasZealotsZealousZeatinsZebecksZebraicZebranoZebrassZebrineZebroidZecchinZechinsZedoaryZelkovaZemstvaZemstvoZenaidaZenanasZenithsZeoliteZephyrsZeppoleZeppoliZeroingZestersZestfulZestierZestilyZestingZeugmasZibethsZiggingZigzagsZikuratZilchesZillahsZillionZincateZincifyZincingZinciteZinckedZincoidZincousZinganiZinganoZingaraZingareZingariZingaroZingersZingierZingingZinkifyZinniasZiplessZiplockZippersZippierZippingZirconsZithernZithersZizzledZizzlesZlotiesZlotychZoarialZoariumZocalosZodiacsZoeciumZoisiteZombiesZombifyZonallyZonatedZonkingZonulaeZonularZonulasZonulesZooeciaZoogenyZoogleaZooidalZooiestZoologyZoomingZooningZootierZootomyZorillaZorilleZorilloZostersZouavesZoysiasZydecosZygomasZygosesZygosisZygotesZygoticZymasesZymogenZymosanZymosesZymosisZymoticZymurgyZyzzyva
ivy and ivory
tablet table
Zigzag ? i think
identify idiot
reject