选A, devote是一个及物动词,后面一定要跟宾语的,如后面没有宾语,只能用它的系表结构/被动结构be devoted to...,此句中devoted to his research work相当于这样一个原因状语从句：Because he was devoted to his research work,因为它的主语和后面主句主语一致,又是一个被动语态句,所以简化为过去分词短语作状语.