Hello Would you please tell me what 's the difference between by and until in negative statements like these ones? A- I didn't get up by nine o'clock. B- I didn't get up until nine o'clock. C- He won't be back by Friday. D- He won't be back until Friday. E- They won't publish my book by March. F- They won't publish my book until March. G- I won't work by the age of 30. H- I won't work until the age of 30. Thank you.
I didn't get up by nine means that at nine o'clock, you were still sleeping, having failed to wake up. I didn't get up until nine means that you had been sleeping but woke up at nine. In these examples, "by x" means that something will not have happened at that date, and does not indicate whether or not it occured later. "Until x" means that after a period of time (or distance) the event will occur. For instance, "Keep going along the road until you reach the church". Until is conditional upon a certain place, time or state being reached.
