Quote by magnificent1rascal
To my knowledge, 'so long as' and 'leave it be' are both valid expressions.
'So long as' is not in SPEU hence I automatically assume its wrong. But I guess 'as...' can be used the same as 'for the duration' and 'so...' can be used as a conditional, like 'provided that'.
The verb of leave is 'to go away from', and let is to allow or permit. 'Leave it be' is a tautology, just like 'free gift' or 'the reason why'.
But I am no English professor and I guess its all in the context, so I stand corrected.
