[majid72]

Hello
Could someone please explain to me 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.

Thanks a lot.