- accidentally
- advice
- affect
- believe
- benefit
- challenge
- coarse
- course
- criticize
- deceive
- definite
- describe
- despise
- develop
- disappoint
- dissipate
- duel
- ecstasy
- effect
- embarrass
- existence
- fascinate
- fiery
- formerly
- humorous
- hypocrisy
- immediately
- impostor
- incident
- incidentally
- latter
- led
- lose
- marriage
- mischief
- murmur
- necessary
- occurred
- opportunity
- parallel
- Philip
- playwright
- preceding
- prejudice
- principal
- principle
- privilege
- pursue
- repetition
- rhyme
- rhythm
- ridiculous
- sacrilegious
- seize
- separate
- shepherd
- siege
- similar
- simile
- too
- tragedy
- tries
- undoubtedly
- until
- villain
Note that a single consonant (other than v) preceded by a stressed short vowel is doubled before -ed and -ing: planned, letting, beginning. (Coming is an exception.)
Write to-day, to-night, to-morrow (but not together) with a hyphen.
Write any one, every one, some one, some time (except in the sense of formerly) as two words.