so…that的意思是“如此…以致于…”，连接的是结果状语从句，如果that后面是一句否定句则可以和too…to句型改写。too…to的意思是“太…以致于不能…”。
改写通常有两种情况：
一、当主从句主语一致时，如：He is so old that he can't look after himself. = He is too old to look after himself.
二、当主从句主语不一致时，如：The desk is so heavy that I can't move it. = The desk is too heavy for me to move.
