adverb or adjective

[navi tasan]

Which of the following are correct:
1-John's program on Monday was about evolution.
2-John's program last week was about evolution.

3-John on Monday talked about evolution.
4-John on Monday was in a cheerful mood.

They are all correct.

However, for 3 and for 4, I’d put the time expression either at the beginning or at the end. This would make the sentence sound better, IMO.

3 On Monday, John talked about evolution.
4 On Monday, John was in a cheerful mood.

or

3 John talked about evolution on Monday.
4 John was in a cheerful mood on Monday.

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