#!/bin/bash
s='yes said holmes answering the look rather than the words it is
so i know all about mccarthy
the old man sank his face in his hands god help me he cried but
i would not have let the young man come to harm i give you my word
that i would have spoken out if it went against him at the assizes
i am glad to hear you say so said holmes gravely
i would have spoken now had it not been for my dear girl it would
break her heartit will break her heart when she hears that i am
arrested'
sed -E 's/(\s[a-z]\s)/ /g'  <<< "$s"

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