dew / do / due are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
dew: (noun) water that has condensed on a cool surface overnight from water vapor in the air.
do: (noun) the syllable naming the first (tonic) note of any major scale in solmization. (verb) get (something) done. (verb) proceed or get along. (verb) create or design, often in a certain way. (verb) carry on or function. (verb) travel or traverse (a distance).
due: (noun) that which is deserved or owed. (noun) a payment that is due (e.g., as the price of membership). (adjective) owed and payable immediately or on demand. (adjective) scheduled to arrive. (adjective) suitable to or expected in the circumstances. (adverb) directly or exactly; straight.
dew: d·UW
do: d·UW
due: d·UW
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)