Which pair of lines from the passage contains a change in intonation?

but all the time / i’se been a-climbin’ on,

and splinters, / and boards torn up,

it’s had tacks in it, / and splinters,

and places with no carpet on the floor— / bare.

well, son, i’ll tell you:
life for me ain’t been no crystal stair.
it’s had tacks in it,
and splinters,
and boards torn up,
and places with no carpet on the floor—
bare.
but all the time
i’se been a-climbin’ on,
and reachin’ landin’s,
and turnin’ corners,
and sometimes goin’ in the dark
where there ain’t been no light.
(from mother to son by langston hughes)