1. Please classify the animals as predators, herbivores or scavengers.
  2. Please classify the sentences into what types.
  3. Please classify the sentences by type/group.
    Please check the above and correct them.
  1. OK.
  2. Not right.
  3. “by type” is OK. “by group” might be OK in the right context, if “group” is defined as a means of classification. Without further context, “group” seems to refer to the result of classification rather than the means (e.g. you would say “classify into groups”).


  1. Can I say as below:
    “Please classify the sentences into types.”?
  2. Can I use ‘categorize’ in place of ‘classify’ in those sentences?
  1. I guess so, but “by type” seems preferable to me, as far as I can tell with no further context.

  2. Yes.

‘classify’ has also another meaning.
For example:
Classify these documents.
= Declare unavailable these documents, as for security reasons.
Am I correct?

Yes, that’s correct. It is an extension of the ordinary meaning. Really it means “classify (documents etc.) as secret/confidential/etc.”, but in suitable contexts the “as secret/confidential” part is omitted and assumed.