results on almost cohen-macaulay modules

let (r;m) be a commutative noetherian local ring, and m be a non-zero nitely-generated r-module. we show that if r is almost cohen-macaulay andm is perfect with nite projective dimension, then m is an almost cohen-macaulay module. also, we give some necessary and sufficient conditions on m to be an almost cohen-macaulay module, by using ext functors.