Question

we arrived home at 9:00 in the evening,( )most people had already had supper.

A at that time B by that time C at which time D by which time 为什么选D？解释~

Answer 1

我认为选 B 和 D 都可
by that time 和 by which time 都有 "届时" "之前“ 之意。
另一同义词是 by then。
by xxx 表示事情已经发生了。
that 和 which 是代词，用来显示关系，意思是 这(个)，那(个) 。
如 the house in which I once lived 我从前住过的房子。
但 by which time 是比较习惯用法。