Matched context for back-flow and expulsion

The page lists matched contexts for back-flow and expulsion.

Share - back-flow	Share - expulsion	Phrase
27.51%	13.56%	prevent {back-flow or expulsion} [perform operation]
6.55%	16.16%	fuel {back-flow or expulsion}
9.86%	10.38%	fluid {back-flow or expulsion}
6.12%	9.03%	gas {back-flow or expulsion}
4.08%	3.43%	air {back-flow or expulsion}