Maintaining in the target language specific contrastive registers in the source language is perhaps impossibly difficult.
The 'strictly necessary' ought to be minimalist, but not impossibly so; this estimate seems plausibly to be precisely that.
Merely attempting to ensure observance of the provisions of the law was almost impossibly difficult.
Since a zero would represent an impossibly precocious acquisition, we replaced such a zero with the age of their oldest observed data point.
The theoretical results depend upon a parameter measuring the slip, but impossibly small values would have to be used to make the theoretical results agree with the experimental ones.
The "problem" condensed almost impossibly broad concerns.
Anyone who declared that a certain treatment would have a stated effect on crop weight irrespective of variety, season, soil conditions or weather would be regarded as impossibly nave.
There was confusion about the rules, uncertainty about the legislation, and an impossibly large number of potential schemes to manage and deliver.