Matched context for exposure and back-flow

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

Share - exposure	Share - back-flow	Phrase
4.55%	27.51%	prevent {exposure or back-flow} [perform operation]
3.13%	9.86%	fluid {exposure or back-flow}
0.92%	6.55%	fuel {exposure or back-flow}
0.95%	2.52%	not {exposure or back-flow}