during which和of which的用法区别`如此题15.The journey around the world took the old sailor nine months,_____ the sailing time was 226 days.A.of which B.during which C.from which D.for which为何用OF?

Time during which a computer is not scheduled for use, maintenance, alteration, or repair.
一台计算机既不准备使用，也未作维护、更换或修理的这一段时间。
After a year's silence (ie a year during which she didn't write), I got a letter from her.
她沉默了一年之后, 又给我来了一封信.
of which
adv. 其中
例句:
The question of which state the minority group should belong to was decided by (a) plebiscite.
该少数民族应归属哪一州的问题已由公民投票表决.
Volleyball is a sport of which I am very fond.
排球是我很喜欢的运动。
By mixing aluminium with other metals, scientists have been able to produce a variety of alloys, some of which have the strength of steel but weigh only one third as much.
把铝和其他金属混合，科学家们能够制造出各种合金，其中一些具有钢一样的强度，但其重量只是钢的三分之一。
Because of this limitation, we use a variety of other pointing devices, the most popular of which is a mouse.
由于这个不足，我们使用一些其他点操作设备，其中最为广泛的是鼠标。

应该从两个词的本身意思来看。
during的本义是 “在……期间”或者“在...期间的某个时候”，你只能说during某个时间发生了什么事情。
of可以表示从属关系，如上文中用of是表示 那九个月中的226天的这个时间。如果把它理解为从属关系，你应该就可以比较容易接受它了吧。
但愿对你有帮助！

定语从句,先行词是"journey",从句变成句子是 the sailing time of the journey was 226 days,which指代The journey 所以用of.用 during 的话就是the sailing time of the nine months was 226 days 这样就不是很通了...

of which ....的
during which 在...期间