hi Andy, I'll try to explain it. "pa" is tagalog prefix which imply an immediate future plan / action (which is to be done now), and it is actually "pa+stem + na (particle)" "(pa)alis na" is translated "about to leave" in english. "paalis na ako ng opisina" ('I'm about to leave the office') "papunta na ako sa liwasan" ('I'm about to go to the park') "patulog na ako ng umalis ka" ('I'm about to sleep when you left.') the prefix "um" is a different thing. it is used with a verb in a PRESENT and PAST action only. "umaalis" - leaving = present tense "umalis" - left = past tense "aalis" - will leave = future (note that prefix 'um' is not used here.) I hope this helps. :)

i agree with with my fellow country man answer. mabuhay "the 3 stars on the sun" cowboy...