I understand that when we use the past continuous tense, our listener usually understands what time we are talking about. Like, "I was working at 10 pm last night."
However, I saw a sentence in a textbook it wrote that "I was in bed asleep at 4.30 this morning." I wonder why it didn't use past continuous tense; can we say "I was being in bed asleep at 4.30 this morning" or not? Plus, I'm not sure if the verb to be can be continuous or not for this case.
Moreover for verbs that can't be continuous, if I write a specific time, I have to use past tense not continuous tense, right? For example, "I saw a very big bird at 10 am this morning." Is it correct to use past tense "saw" in this case?