Student or Learner
Hello!Your help is appreciated here.
1. We stayed there for three years,during which time we developed our friendship.
2.You'd better not go shopping after 8 o'oclock at night,by which time all the stores have been closed.
Can we use "when " to replace "during which time " in sentence 1 and " by which time " in sentence 2?
For 2, yes. For 1, I don't like it, as it fails to show the gradual nature a growing friendship.