答案：B

答案：B　考查代词用法。此处it作形式宾语，真正宾语是when the weather is like this。如果主句谓语是表示爱憎类的动词，如like/dislike/hate/appreciate，且其宾语为一个宾语从句时，则一般把it放于其中作形式宾语，后面再加上if或疑问词引导的宾语从句。再如：I dislike it when people talk with their mouths full.我讨厌人们一边嘴里满是东西，一边谈话。I'll appreciate it if you could open the window for me.如果你能帮我打开窗户，我将不胜感激。