1. I'm busy till late in the evening.
2. I'm busy till late this evening.
3. I'm busy till late every evening.
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Does #1 mean #2 or #3? Can #1 mean both? Which one is common?
#2 applies only to today
#3 means what it says -- every evening
#1 is similar to #3, but is just a general observation. Most of the time you are busy, but there may be evenings when you are free. You might have a job which keeps you at work late, but you have weekends or other days off. In that case, it's be quite normal to say that you are busy in the evening, but it's not a strict rule.