Question

【题目】The subject has been （谈到，查阅）to cursorily粗略in the
preface.序言

Answer 1

【答案】referred
【解析】referred 句意：在序言里这个主题已经被提到。refer to提到，谈到。此处是现在完成时态的被动语态，故填过去分词referred 。