To distinguish the Minimal Supersymmetric Standard Model (MSSM)
from a general two-Higgs-doublet model (THDM), one needs to test the
mass relation and the coupling of Higgs bosons.
In the MSSM, the masses of the charged Higgs boson (H^\pm) and the
CP-odd scalar (A) are related by M_{H^+}^2=M_A2+m_W2, and the coupling 
of W-A-H^+ is fixed by gauge interaction, therefore, the tree level 
production rate of q \bar q' \to W^{\pm \ast} \to A H^\pm
depends only on one supersymmetry parameter -- the mass (M_A) of A.
To a good approximation this conclusion also holds at the one-loop 
level. We discuss the potential of the CERN LHC to detect the signal 
event q \bar q' \to W^{\pm \ast} \to A (\to b {\bar b})
H^\pm (\to \tau^+ \nu_\tau ) with \tau^+ \to \pi^+ {\bar \nu_\tau}.
Moreover, we show that in a general THDM the above mentioned mass 
relation is absent and the self-coupling of the Higgs boson, in contrast
to the MSSM, can receive a 100% radiative correction from scalar loops.