Fail To Pass


Go from FAIL to PASS in only four steps, changing one letter at a
time and making a good English word at each step.

F A I L
- - - -
- - - -
- - - -
P A S S 
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  v
Answer:
Fail
Fall
Pall
Pals
Pass

Could also be done as 
Fail
Pail
Pall
Pals
Pass