Is it okay to put "later" right behind the "40 minutes" here?
Native speaker’s answer
Rebecca
No, "later" would be superfluous here as the speaker has already indicated they have an appointment in 40 minutes. If the speaker did not indicate a specific time for the appointment, adding "later" in this sentence would be okay. Remember that "later" is general whereas "in 40 minutes" is more specific, so the effect of each of these time cues is also different. Ex: I have an exam in an hour. Ex: I have an exam later.