英语语法It's getting coldIt's 主getting谓cold宾如此划分是否正确,还有这里只是写了it'

英语语法,成分划分?It's getting cold.为什么有人说,it是主语,is getting是系动词,cold it's getting dark. It's getting cool it's getting cold and take care of your health it's getting cold.__ take a jacket with you? it's getting dark.M____. _____!It's getting dark Spring is getting near and it's getting w___. It's getting and (warm)in spring. it's getting bigger and _(clean) It's Getting Dark In Here 歌词 It's getting darker and darker outside.