  Separately, neither electromagnetic (EM) observations nor gravitational wave
(GW) observations can distinguish between the $f(T)$ model and the $\Lambda$CDM
model effectively. To break this degeneration, we simulate the GW measurement
based on the coming observation facilities, explicitly the Einstein Telescope.
We make cross-validations between the simulated GW data and factual EM data,
including the Pantheon, H(z), BAO and CMBR data, and the results show that they
are consistent with each other.
  Anyway, the EM data itself have the $H_0$ tension problem which plays
critical role in the distinguishable problem as we will see.
  Our results show that the GW$+$BAO$+$CMBR data could distinguish the $f(T)$
theory from the $\Lambda$CDM model in $2\sigma$ regime.
