Question

correct the one word that is spelled incorrectly.
the clock of the long now, or the 10,000 year clock, is designed to keep correct time for ten thousand years. over that time, it will be powered primarily by human winding and will require regular maintainance.

Explanation:

The word "maintainance" is misspelled. The correct spelling of the word related to the act of maintaining something is "maintenance". We check the spelling of each word in the sentence and identify that "maintainance" has an incorrect letter (the extra 'i' before 'nance' is wrong; the correct root is "maintain" but the noun form is "maintenance" with the 'i' removed after 'tain').

Answer:

The misspelled word is "maintainance", and the correct spelling is "maintenance".