Use of imperfect in Luke 23:34

Hi - 
I have a question about the use of the imperfect form of legw in Luke 23:34 
(Jesus *said*, father, forgive them for they do not know what they do.) 
My lexicon says that only the present and imperfect active and passive forms 
of legw are in use in the New Testament. Should I understand the imperfect 
here as actually being completed in the past (since it cannot reasonably be 
construed to mean repeated action (i.e. 'Jesus kept saying'). Why are only the 
present and imperfect forms of legw used? Is there any particular significance 
to the use of the imperfect in Luke 23:34? 
BTW, does someone have a good list of the transliteration for Greek - there 
were a few floating around a month ago or so buit I seem to have misplaced 
Mary Ann Davidson 
Kumai kumai kanalu nui mai kahiki mai		 
Alo poi ipu ku mai ka pohuehue 
Hu kai ko oloa 
	Arise, arise o great surfs of Kahiki 
	The powerful curving waves arise with the morning glory vine 
	Well up, long-ranging surf!