寒冷的冬天是the cold winter还是cold winter?

寒冷的冬天是the cold winter还是cold winter? 是in a cold winter 还是on a cold winter? 是in cold winter nights还是on cold winter nights 为什么“在一个寒冷的冬天的早上”的英语是“On” a cold winter morning而 请问是In a cold winter morning 还是 on a cold winter morning? ( ) a cold winter night.是用in还是on? 是on a cold winter morning还是in? on a cold winter day,还是in a cold cold winter day cold winter month前应加on还是in? （ ）a cold winter in还是on ( )cold winter days The winter here is cold.这里的here是什么意思?