The evidence for the continuing accretion of gas by the Milky Way involves high-velocity clouds, or HVCs--mysterious clumps of hydrogen, moving rapidly through the outer regions of the galaxy.
There is no way to verbally shorten the term high-velocity clouds.
( z1 possible :polarity - :ARG1 ( z2 shorten :ARG1 ( z3 term :ARG1 ( z4 cloud :mod ( z5 velocity :ARG1-of ( z6 high ) ) ) ) :manner ( z7 verbal ) ) )