On hearing of the case, Conan Doyle was______that the man was innocent and immediately went to work to ascertain the truth for him.
【正确答案】
A
【答案解析】解析：本题考查单词辨析。be convinced of／that(相信……)符合句意。conceive(设想，想出)常作为主动语态来使用；relieve，减轻，缓解；dismay(使……沮丧，使……惊愕)放在句子前半句是合理的，对这个人的无辜表示惊讶，但是后面说到开始去为他查明事实，不合逻辑。