Question

看一道定语从句的问题，高手进！要多少分给多少分~

The book was written in 1946,___the education system has witnessed great changes
a.when B.during which C.since then D.since when
给出答案，给出详解
然后，
解释一下，除了A以外的3个选项的用法~或者给个例句~拜托了~

Answer 1

D

a: 如果选when，其引导的从句修饰1946，时态应该为过去式或者过去完成时。而句子时态为现在完成时，所以，a错。

b: during which 用起来比较复杂，尽管是指一段时间，但用起来要注意。同样，时态也要和主句时态吻合，现在完成时很显然也否定了 b 选项；
例句：I watched a movie during which I fell asleep.

c: since then 是介词短语，从此（指某个时间以后），不是从句的引导词，所以c错。如果在since then 前加上 and 就可以了，变为2个并列句。
例句： The company started as a small local business 10 years ago and has grown a lot since then.

d: when 引导的非限定性定语从句，修饰1946。从句可改写成： the education system has witnessed great changes since 1946.

Answer 2

when强调动作在过去发生,since强调时间的起点并延续.完成时的事态中表述时间为一个持续性阶段的用since. 这句是现在完成时,选D
since when表示动作延续到现在
B during的本义是 “在……期间”或者“在...期间的某个时候”，eg: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。
He was very diligent when he was in the university, during which he was awarded the scholarship several times.
他在大学期间非常勤奋，那段时间他几次获得了奖学金。
C.
Since then 意思是“从那之后”
eg:Prices have gone up since then.
从那时开始就涨价了。
She's been studying hard since then.
打那儿起， 她就努力学习了。

D.就是本题的用法

Answer 3

先给你几个例句：
Vacation: A period during which you learn where to stay away from next year.
度假：一段时间，在这段时间里你知道了明年千万别去哪里。
They have been good friends since then.
从那时起他们就一直是好朋友。
Since when have you stayed here ?
你从什么时候起住在这里的?

Since when 什么时候开始的？；什么时候开始；从那时以来
since then 从那时以来

从例句可以看出，since then 最合适。它引导的时间范围是现在完成时，与题目相符。
since when 有疑问的意思。

Answer 4

选D
从句中用了has，现在完成时态，表示动作从1946年持续到现在，排除A和B。
从句中when指的是1946，整个从句作1946的定语，then不能起定语从句作用。

Answer 5

这种题目有没有语境啊？语法上好像几个都可以，只是意思不同，
a、那时候
b、在……之间
c、自从那以后
d、好像没有这种用法

选a比较大可能。