Regardless of whether you are a scholar or are basically wanting to compile a summary of tough terms for the spelling bee Competitiveness, this list of 100 tough terms to spell is a good source to make use of. For example, "apple" results in being "apples"; "tree" turns to "trees"; https://dsl-english-live82603.bloggazzo.com/27582334/an-unbiased-view-of-spelling-rules-in-english