至今未见during time的用法during which time等于during when,用以引导非限制性定语从句，属于介词+when/where引导定语从句的范畴。如果作为先行词的时间名词在主句、从句中都是作介词宾语，充当时间状语，但介词前后发生了变化，那么，定语从句的引导词就要使用“介词+ when /which time”（介词的使用要取决于从句中的搭配需要）。如果作为先行词的时间名词在主句中作主语、宾语（作介词宾语时，主句从句中的介词是同一个介词）、表语等，加上适当的介词后在定语从句中时间状语，那么引导词就要使用“介词+which”（介词的使用要取决于从句中的搭配需要）。①They stayed with me for two weeks, ____they drank all the beer I had.A. for which B. which time C. during which time D. during which②The book was written in 1946, ___ the education system has witnessed great changes.�A. when B. since which�C. since then D. since when有类似用法的还有“介词+where":① He stood at the window, ____ he could see what was happening.A. from where B. from which C.which D. at which② His head soon appeared out of one of the second storey window, from where he could see nothing but trees．
Moser～子涵
