You will be given mystery words with four consecutive letters shown, with blank spaces for where the other letters should be. Your job is to find what words they are, and their relation. Hyphenated words will show where the hyphen is.
_ _ R K S C _ _ _
_ _ N E G L _ _ _
_ _ _ T L E - C _ _
Hint gives three letters that are used in the words, but it won't say what words they belong in.