$A$ and $B$ possess unequal dimensional formula then following operation is not possible in any case:-
$log (A -B)$
$sin (A + Bx)$
$e^{(AB)}$
$\tan \left[ {\frac{A}{B}\left( {\frac{B}{A}n} \right)} \right]$
If velocity$(V)$, force$(F)$ and time$(T)$ are chosen as fundamental quantities then dimensions of energy are