Assertion list for term "become impassable".

Results from Ascent++: 5
road CapableOfbecome impassable 0.48
ocean CapableOfbecome impassable 0.33
area (aspect of park) CapableOfbecome impassable 0.29
caution CapableOfbecome impassable 0.16
passage CapableOfbecome impassable 0.16