the time during whichThe time when I first met him was a very difficult period of my lifewhen为什么可以改为during which还有百度上说的during which 和during which time的区别按照：看前面修饰的名词是指具体的时间还是

Question

the time during which
The time when I first met him was a very difficult period of my life
when为什么可以改为during which
还有百度上说的during which 和during which time的区别按照：看前面修饰的名词是指具体的时间还是一个含有时间概念的名词,如果是具体时间,则用during which time；如果是后者则用during which

Answer 1

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during +一段时间时,就可能用during which作为引导词如：
Do you still remember the weeks during which we stayed together?
We are to study in this university for fouryears,during which we shall prepare ourselves well for the society.
我们将在大学学习四年,在此期间,我们要为进入社会做好准备.
而during which time,往往可以换成：during that time指先行词的.
如
The interview lasted less than a minute,during which time I was sacked,not lauded.
但是谈话不到一分钟就结束了.我并未受到嘉奖,相反我被开除了.
这里就是：
The interview lasted less than a minute,and during that time I was sacked,not lauded.