  We construct projective covers of irreducible V-modules in the category of
grading-restricted generalized V-modules when V is a vertex operator algebra
satisfying the following conditions: 1. V is C_{1}-cofinite in the sense of Li.
2. There exists a positive integer N such that the differences between the real
parts of the lowest conformal weights of irreducible V-modules are bounded by N
and such that the associative algebra A_{N}(V) is finite dimensional. This
result shows that the category of grading-restricted generalized V-modules is a
finite abelian category over C. Using the existence of projective covers, we
prove that if such a vertex operator algebra V satisfies in addition Condition
3, that irreducible V-modules are R-graded and C_{1}-cofinite in the sense of
the author, then the category of grading-restricted generalized V-modules is
closed under P(z)-tensor product operations for z in C^{\times}. We also prove
that other conditions for applying the logarithmic tensor product theory
developed by Lepowsky, Zhang and the author hold. Consequently, for such V,
this category has a natural structure of braided tensor category. In
particular, when $V$ is of positive energy and C_{2}-cofinite, Conditions 1--3
are satisfied and thus all the conclusions hold.
