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The
Determiner
  four
Numeral
  regiments
Noun
  formed
Verb
  four
Numeral
  battalions
Noun
retaining
Verb
  their
Pronoun
  previous
Adjective
  names
Noun
  in
Adposition
  the
Determiner
  titles
Noun
.

The four regiments formed four battalions, retaining their previous names in the titles.
Words and sentences
New
formed

simple past and past participle of form

New
four

New
battalions

plural of battalion

New
retaining

New
previous

New
names

New
in

New
regiments

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