  We generalize the result of Kawamata concerning the strong version of
Fujita's freeness conjecture for smooth 3-folds to some singular cases, namely,
Gorenstein terminal singularities and quotient singularities of type 1/r(1,1,1)
and of type 1/r(1,1,-1). We generalize furthermore the result of that to
projective threefolds with only canonical singularities for canonical and not
terminal singularities. It turns out that the estimates in the first three
cases are better than the one for the smooth case, which it is not in the
fourth case. We also give explicit examples which show the estimate in the
fourth case is necessarily worse than the one for the smooth case.
