it is raining all day这句话里IT做什么 形式主语?还有这句话有错吗

It is raining all day同义句 it is raining all the day.改为同义句 it is raining ___ ____ ____ It is raining all day.同意句好的+分 It is not raining at all的阅读答案急! 英语翻译now all it has to do is stop raining.是不是all (it has to do ) is (stop raining)? it is raining all day 还是it is rainy all day 哪个对 it is raining是什么意思? It is raining (heavy). It is raining there.对“raining提问 写出同一句1：It is raining all day. It is ………… day? it is raining,as usual it is raining,as usual It's raining all day 中raining 为啥要+ing It is raining cats and It is raining cats and It is raining now.It_____yesterday. It is raining cats and It is raining _____ outside. 英译汉;It is raining heavily.