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?就是說用in是時候不用中間的of？可是我看你在百度知道上回答另一個問題時說“在前天早上”用in the morning of the day before yesterday如果指某一天的上/下午晚上時，介詞用on，如果泛指的“在上午/下午晚上‘時，介詞用in。