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.
Clouds can not move at a high veloctiy.
( z1 possible :polarity - :ARG1 ( z2 move :ARG1 ( z3 cloud ) :manner ( z4 veloctiy :ARG1-of ( z5 high ) ) ) )