题目

定语从句的两问题,
1.定语从句The book was written in1946,___the education system has witnessed great changes.
A.when B.during when C.since then D.since when
这是一高考题,据说是相当与since which time
然而我又遇到这样一道题,如
In the office I never seem to have time until after 5:30 p.m.,____ many people have got home.
A.whose time B.that C.on which D.by which
如果就选答案的话,只有选D,答案也是D.但是这就与上题不就冲突了吗,应该是by which time或是by when?

提问时间：2021-04-08

答案

第一句分析正确.
第二句by which就是by which time,因为主句有一个time,为避免重复就不说time了.
when一般用作疑问副词；但有时也可用作疑问代词,作since, until, up to 等少量几个介词的宾语,如until when, since when, up to when.
按道理来讲,第二题的by which time就是等于by when.但语言不仅要讲道理,更要讲习惯.再合乎逻辑的说法,如果大家口头上都不这样说,那也只能认为它是错的.by when这种说法目前我还没见过.