He came back ____ a cold morning.用in 还是用on

He came back ____ a cold morning.用in 还是用on in a very cold morning 还是用on a very cold morning,到底是用in 还是on in a cold morning还是on a cold morning? 是on a cold morning 还是in a cold morning? 请问是In a cold winter morning 还是 on a cold winter morning? 是on a cold winter morning还是in? ( ) a cold morning of november,on还是in? 用on a cold morning 、 on the morning of september 、 in the mo in a cold day 还是 on a cold day 用in 还是 on He came here___a cold morning. on a ___ morning , he came back home. A:rain B:rainy C:rains __a cold morning on还是 in