Usually the use of nonrestrictive
that shows that a writer has muddled what he has wanted to set down, as in the following example from a serious article:
> One of the most important recent developments in neutral hydrogen studies of our Galaxy has been the discovery of high velocities in the centre and in regions away from the plane,
that I have mentioned.
Despite the comma - and the corresponding prosodic separation if this is read aloud (a separation that is essential if
plane were not to be thought the antecedent head) - it seems likely that the writer originally wanted the relative clause to be restrictive, as it could readily have been if placed earlier:
> ... has been
the discovery that I have mentioned of high velocities ...
However, this position of the relative clause violates the rule that prepositional phrases precede relative clauses as postmodifiers, producing a rhetorically unacceptable sentence.
Autorzy nie podają przykładu przekształconego zdania, w którym te
relative clause byłoby użyte prawidłowo. Czy mam rozumieć, że nie da się tutaj użyć
relative clause? Czy można wstawić
aforementioned przed
discovery?