  We conduct a comprehensive spectro-temporal analysis of repeating Fast Radio
Bursts (FRBs) utilizing nine distinct sources, the largest sample to date. Our
data set includes 175 sub-bursts and 31 multi-component bursts from 11 data
sets, with centre frequencies ranging from 149--7144 MHz and durations spanning
from 73 $\mu$s--13 ms. Our findings are consistent with the predictions of the
Triggered Relativistic Dynamical Model (TRDM) of FRB emission. We affirm the
predicted quadratic relationship between sub-burst slope and central frequency,
as well as a linear dependence of the sub-burst bandwidth on central frequency
that is consistent with mildly-relativistic Doppler broadening of narrow-band
emission. Most importantly, we confirm the sub-burst slope law, a predicted
inverse relationship between sub-burst slope and duration, to hold consistently
across different sources. Remarkably, we also discover that the drift rates of
multi-component bursts follow the same law as the sub-burst slopes, an
unexplained result that warrants further investigation. These findings not only
support the TRDM as a viable framework for explaining several aspects of FRB
emission, but also provide new insights into the complex spectro-temporal
properties of FRBs.
