  Context. Traditionally, supersonic turbulence is considered to be one of the
most likely mechanisms to slow down the gravitational collapse in dense clumps,
thereby enabling the formation of massive stars. However, several recent
studies have raised differing points of view based on observations carried out
with sufficiently high spatial and spectral resolution. These studies call for
a re-evaluation of the role turbulence plays in massive star-forming regions.
Aims. Our aim is to study the gas properties, especially the turbulence, in a
sample of massive star-forming regions with sufficient spatial and spectral
resolution, which can both resolve the core fragmentation and the thermal line
width. Methods. We observed NH3 metastable lines with the Very Large Array
(VLA) to assess the intrinsic turbulence. Results. Analysis of the turbulence
distribution histogram for 32 identified NH3 cores reveals the presence of
three distinct components. Furthermore, our results suggest that (1) sub- and
transonic turbulence is a prevalent (21 of 32) feature of massive star-forming
regions and those cold regions are at early evolutionary stage. This
investigation indicates that turbulence alone is insufficient to provide the
necessary internal pressure required for massive star formation, necessitating
further exploration of alternative candidates; and (2) studies of seven
multi-core systems indicate that the cores within each system mainly share
similar gas properties and masses. However, two of the systems are
characterized by the presence of exceptionally cold and dense cores that are
situated at the spatial center of each system. Our findings support the
hub-filament model as an explanation for this observed distribution
