本句结构是：The time was a period所以,这里the time就是the period of time的意思,因此,后面的引导词用when时,可用：during the time替代,也就是during which]而且,先行词是一段时间（不一定是time),又可以说durin...四年和一分钟不都是具体的时间吗 为什么We are to study in this university for fouryears, during which we shall prepare ourselves well for the society不用during which time应该是一段时间，不是具体时间。你可以说：during one minute; 也可以说：during the four years, 所以，可以用during which，因为which就是代表先行词的。倒是具体的时间点不用during,比如：5：15就是时间点，而不用的。还有某年也是。如：I never forget the year of 2008, in which the Beijing Olympic Games were held.可是一分钟的时候又用during which time.这多一个time要怎么理解？一分钟并不一定要用during which time的。He waited for us one minute, when(during which) we were in the teacher's office.