She plans to expand the lecture series into a book.她计划将这个系列讲座扩写成一本书。This book is an expansion of a lecture series.本书是一系列讲座的扩充。The society decided on a lecture series and appointed a committee to determine the speakers, the dates, etc.学会决定举办系列讲座，并委派一个委员会具体择定讲员、日期等。