“…Recall that a ring R is left principally injective (fP-injective) if every principal right ideal is a right annihilator, and the ring R is left generalized principally injective (GP'-injective) if, for any 0 ^ a e R, there exists n > 0 such that a" ^ 0 and a"R is a right annihilator. The detailed discussion of left P-injective and left GP-injective rings can be found in [3,7,12,15,16,17,22,23,24,26]. Clearly, every left AP-injective ring is left P-injective and every left AGP-injective ring is left GP-injective.…”