Ok for example.Suppose you were a student and you were supposed to have a class at eight o'clock but you didn't come until eight thirty. There could be two outcomes: 1. Your teacher would say ,why are you late? In such a context,your teacher wanted you to explain why you were late. **2. Your teacher would say,你怎么能迟到呢？how can you be late? Your teacher means you shouldn't be late. This sentence is in the same usage with 我怎么能回家呢？ They both use rhetorical and emphatic tones.

The translation in the context is not very accurate. 怎么 in here is used in a rhetorical mood and strengthen mood. The woman here says the time difference is not over, why should I go back? In fact, what she was trying to say was that the jet lag had not turned upside down, and she didn't think she should go back.

怎么，commonly used to inquire about the situation, nature, way, cause, question, action, etc., commonly used as a question language. Ask for nature, manner, cause, action, etc. 他们怎么还不回来？ta men zen me hai bu hui lai Why aren't they back? Used for virtual reference ,refers to an event. 不知怎么，她很气恼 bu zhi zen me ta hen qi nao Don't know why, she's angry. stands for degree 也许它留给你的印象不怎么深 ye xu ta gei ni liu xia de yin xiang bu zen me shen Perhaps it left you with a less impressive impression Stands for anyway,in any case 我怎么也猜不透 wo zen me ye cai bu tou I can't guess in any guess (My English is poor ,I don't know if you can read my writing.)