in such a manner to be maximally efficient. Just the constituent that is focused by the question word is uttered. The elided material in the examples in this article is indicated using a smaller font and subscripts:

::Q: Who walked the dog? A: Tom _{walked the dog}. - Subject noun as answer fragment
::Q: Whom did you call? A: _{I called} Sam. - Object noun as answer fragment
::Q: What did you try to do? A: _{I tried to} Fix the hard drive. - Verb phrase as answer fragment