I have been looking at these sentences a little too closely, and it's starting to get a bit blurry all of them are starting to look correct. I am especially interested in the third one, which mixes simple past with present perfect. I would like a show of hands is it unforgivably wrong? perfectly acceptable? weird or broken English? a construction frequently used by some native speakers, though technically wrong?

I just now lost the letter I'd kept so long. (okay) I just now lost the letter I kept so long. (okay) I just now lost the letter I've kept so long. (okay) Some time ago I lost the letter I'd kept so long. (okay) Some time ago I lost the letter I kept so long. (okay) Some time ago I lost the letter I've kept so long. (bad probably wrong) I still have the letter I've kept so long. (okay) I still have the letter I kept so long. (bad probably wrong)
Ross
Roebuck, South Carolina
http://community.webshots.com/user/ross klatte
http://www.ncplenty.org/businessplan.pdf
It is 4 miles from Denmark to Finland, and 4 miles from Denmark to Sweden, but it is 9 miles from
Denmark to Norway.
I have been looking at these sentences a little too closely, and it's starting to get a bit blurry all of ... from Denmark to Finland, and 4 miles from Denmark to Sweden, but it is 9 miles from Denmark to Norway.

Three is wrong. The condition described by 'Have kept so long' must extend to the present, the moment of utterance, and it doesn't.

john