akgrl13 it's very helpful, thank you :)

Yeah, he's right, it should be "fool's errand" because it's possessive. Even native speakers make mistakes sometimes, but good job catching that ;) "I have been reading CNN News, and they quoted someone as saying "a fools errand," but my dictionary entry says "a fool's errend." Why is the apostrophe dropped here?" Hope that helps :)

calvin_lau, Your dictionary is correct. The spelling is "fool's errand". The CNN article contains a spelling error. Good work!