David Mulroy asked if a linguist would agree with his explanation: 

>My explanation is the present perfect is used to characterize an action
that
is complete ("perfect") but was completed so recently that it is still
relevant to one's understanding of the present moment.  "The Chinese have
refused to return our spy plane," but not "Brutus has assassinated
Caesar."  <

I am a linguist (of the Hallidayan functional type) who has spent many
years 
teaching college composition, including the grammar that such a course
entails,
and I have long used a similar explanation.  Present perfect refers to past

actions that still have an effect in the present.

Carolyn Hartnett
[log in to unmask]

To join or leave this LISTSERV list, please visit the list's web interface at:
     http://listserv.muohio.edu/archives/ateg.html
and select "Join or leave the list"

Visit ATEG's web site at http://ateg.org/