in winter泛指在冬天，in the winter特指在某個冬天。上下文應該有所指。in the winter是特指的某個冬天比如：In the winter,I came to Haerbin for the first time. 這個冬天， 我第一次來到了哈爾濱。而 in winter是泛指冬天。比如：It always snows in Haerbin in winter. 哈爾濱的冬天總會下雪。