in winter :on winter哪个是正确的?

in winter 还是 on winter 是in a cold winter 还是on a cold winter? 在寒假是on winter holiday还是in winter holiday 是in cold winter nights还是on cold winter nights ( in/on/at )winter on winter day 还是 in winter day on winter evening还是in winter evening in winter holiday还是on winter holiday 是on winter 还是 in of at 英语中冬天是第几季 是in snow in winter还是on sonw in winter after/in/on/at cold winter night 哪个对? 是at winter 还是in winter?