Sentence:  By moving the term `` Republic '' to lower case , <WSD>substituting</WSD> the modern phrase `` move ahead '' for the stodgy `` keep '' , and by using the Postmaster 's name on every envelope ( in caps , of course , with the `` in spite '' as faded as possible ) , the slogan cannot fail . 
Meaning of the word marked with <WSD> tags:  put in the place of another; switch seemingly equivalent items