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Hyphens, En Dashes, Em Dashes
Q. Consider the following sentence: “I am bored by exhibitions of folk-, line-, and square dancing.” Are the hyphens correct even though the compounds contain no hyphens? Similarly, “He was a poor student in both middle- and high school.” I believe the hyphen is needed here, but will defer to your opinion.
A. In both sentences, the meaning is clear without hyphens. If you feel that something more is needed, repeat the missing element: in both middle school and high school.