5Is it possible to use until/before in sentences a. and b. to paraphrase sentence 1?
1) It was 8:00 pm when she left.
a. She didn't leave until 8:00 p.m. Yes. 'Until' can suggest a longer stay, or at least one that feels longer, than 'when'.
b. She didn't leave before 8:00 p.m. Yes. This can mean that she left at or after 8.