By that time = at that time??

[Apollo_Doutrinador]

"By then" = "then"? "by that time" = "at that time"?

Which the difference?? What does "by" means? Which the synonyms to the word "by" on this case (by then, by that time)?

[BobK]

"By then" = "then"? "by that time" = "at that time"?

Which the difference?? What does "by" mean[s]? Which the synonyms to the word "by" on this case (by then, by that time)?

"By" refers to an extent of time: "By that time the building was nearly finished"/"You should be on question 5 by now". All the time up to the point of speaking, something has been happening.

"At" refers to a point in time: "At that time, and not before, you can go home"/"The train arrives at 15.09"/"We go home at 16.00."

b

[Apollo_Doutrinador]

BobK,

Thank you!