What did he do in the morning the day before yesterday?
=What did he do on the morning of the day before yesterday?他前天上午做什么了?就是说用in是时候不用中间的of？可是我看你在百度知道上回答另一个问题时说“在前天早上”用in the morning of the day before yesterday如果指某一天的上/下午晚上时，介词用on，如果泛指的“在上午/下午晚上‘时，介词用in。