How to know...

[Neytiri Na'Vi]

How do you know when to use the right word, for example, what= Kempe or Phem, What thing = 'upe or peu, where = pesenge or tsengpe, why = lumpe or pelun? How do you know wich one is the right one to use in a sentence??? Tsmukan, tsmuke Rutxe srung si....

[Tirea Aean]

How do you know when to use the right word, for example, what= Kempe or Phem, What thing = 'upe or peu, where = pesenge or tsengpe, why = lumpe or pelun? How do you know wich one is the right one to use in a sentence??? Tsmukan, tsmuke Rutxe srung si....

They are the same. pick the one that sounds the best to you.

Pehem = kempe
'upe = peu
krrpe = pehrr etc.

there is no difference.  tho somethimes you might have to put a case suffix on, in that case, it is MY habit to use the pe[] form instead of the []pe form.

[Kemaweyan]

Besides please note that there is always lenition after pe+ Lenition is a changing of consonant via this scheme:

tx → t
kx → k
px → p
ts → s
t → s
k → h
p → f
' → nothing

For example, kempe is kem + pe, but pe + kem = pehem; or 'u + pe = 'upe, but pe + 'u = peu (without glottal stop)

[Kì'eyawn]

... tho somethimes you might have to put a case suffix on, in that case, it is MY habit to use the pe[] form instead of the []pe form.

I have the same habit.  If it's going to have a case ending added, i tend to use the pe[...] form.

So, while both are correct (AFAIK), i would probably say Peut tse'a ngal? rather than 'Upet tse'a ngal?

[Tirea Aean]

yeah. thats true. i forgot to emphasise more that pe causes lenition.

and thats just my habit cuz it makes more sense to ME.