It's so heavy that I can't carry it.划分一下这个句子成分主语,等成分还有呢，谓语呢，等还有呢，请二楼的补充完整。so heavy that I can't carry it.又是怎么划分的

补充一下：that I can't carry it是个从句啊，前面的so和这个从句一起作为状语。that是引导代词，在that I can't carry it里面指代后面的一句话I can't carry it。至于I can't carry it的结构一楼已经说过了。
It is heavy是主干成分，it 主语，is谓语（系动词），heavy是表语，是主系表结构。
so XXX that是固定结构，修饰heavy，算是状语吧，就是说heavy的程度达到了I can't carry的程度。

It(形式主语)is (谓语) so heavy that I can't carry it.

It is so heavy.这个是最基本的句子。
heavy到什么程度呢：I can't carry it.
中间用that连接。

首先It's so heavy是一个原因状语从句，在这个从句中It是主语，is so heavy是表语。that是关系代词。I can't carry it是主句，其中I是主语，can't carry 是谓语，it是宾语。

It's so heavy that I can't carry it.it是整个句子的主语.is是整个句子的谓语.heavy是表语,so是heavy的程度修饰词.that I can't carry it是状语从句.状语从句的句子成分划分如下：that为连接词,引导状语从句.I为从...

这是经典的so that强调句型（本身就是要熟背的）
主语：it (指代要拿的东西)
系动词：is
表语：heavy
so是副词，修饰heavy （副词修饰形容词）
that开始是从句
从句主语I
助动词can't
谓语动词：carry
谓语动词的宾语：it
这句话的意思是，太沉了，我根本拿不动