Ardith Hinton:

AH> IMHO  what  he's suggesting is that if you don't want to
AH> overuse the verb "speak" you  could  correctly  say  "he
AH> should not (do so)" or "he ought not to (do so)".  :-)

No, I proposed only the following amendment:

  When  a  person is in a company of friends he never speaks
  formally.  And he should not, [or] And he ought not to.

and commented on the impropriety of using `to' in place of a
verb  from  the viewpoint of common sense and general logic.
By the way, repetition is not always cacophonic[1].   It  is
even recognised as a figure of speech!

Now  that  have read it again, I think that "the company" is
much better than "a company" (of friends).
____________________
1. as an antonym of `epiphonic'.

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 * Origin: nntps://fidonews.mine.nu - Lake Ylo - Finland (2:221/6.0)