  We present new ALMA observations of CO, CN, CS, HCN and HCO$^{+}$ absorption
seen against the bright and compact radio continuum sources of eight massive
galaxies. Combined with archival observations, they reveal two distinct
populations of molecular clouds, which we identify by combining CO emission and
absorption profiles to unambiguously reveal each cloud's direction of motion
and likely location. In galaxy disks, we see clouds with low velocity
dispersions, low line of sight velocities and a lack of any systemic inflow or
outflow. In galactic cores, we find high velocity dispersion clouds inflowing
at up to 550 km/s. This provides observational evidence in favour of cold
accretion onto galactic centres, which likely contributes to the fuelling of
active galactic nuclei. We also see a wide range in the CO(2-1)/CO(1-0) ratios
of the absorption lines. This is likely the combined effect of hierarchical
substructure within the molecular clouds and continuum sources which vary in
size with frequency.
