OET interlinear LAM 5:20

uW Translation Notes:

Note 1 topic: figures-of-speech / rquestion

לָ֤⁠מָּה לָ⁠נֶ֨צַח֙ תִּשְׁכָּחֵ֔⁠נוּ תַּֽעַזְבֵ֖⁠נוּ לְ⁠אֹ֥רֶךְ יָמִֽים

(Some words not found in UHB: to/for=what to,perpetuity do,you(pl)_forget_us do,you(pl)_abandon_us? for,length_of days )

The writer is using the question form to express anguish over feeling abandoned by God. If a speaker of your language would not use the question form for that purpose, you could translate these as statements or as exclamations. Alternate translation: [Surely you have forgotten us forever, you have forsaken us for so long]

Note 2 topic: figures-of-speech / idiom

לְ⁠אֹ֥רֶךְ יָמִֽים

for,length_of days

The writer is using for the length of days as a common expression of the culture to mean “for a long time.” If this phrase does not have that meaning for your readers, you could use a comparable expression from your language that does have that meaning, or you could state the meaning plainly. Alternate translation: [for a very long time]