Shenyang is very cold in winter./ Winter is very cold in Shenyang.
句意:沈阳在冬天很冷。
分析句子可知,it指代的是天气very cold。主语改为Shenyang,系动词is和表语very cold保持不变,最后写时间状语in winter。故答案为Shenyang is very cold in winter.
或者,将winter作为主语,系动词is和表语very cold保持不变,最后写地点状语in Shenyang。故答案为 Winter is very cold in Shenyang.