中文摘要：

给出了EP-内射环的一些等价定义,举例说明了EP-内射环未必是GP-内射环。证明了：若R是半完全的左EP-内射环,且Soc（RR）在RR中本质,则R是左,右Kasch环。

英文摘要：

Some equivalent definitions of EP-injective rings are given. An example is given to show that EP-injective ring needs not be GP-injective. We prove that assume that R is semiperfect and left EP-injective. If Soc （RR） is essential inRR,then R is left and right Kasch.