same可以是形容词、代词和副词。无论作为何种词类，通常都与the 连用。

the same 可后接as比较分句，该分句常采用省略形式。

It's about the same age as our son. 

the same为形容词作定语，the same age as our son (is).

I have the same book as is laid on the desk.

the same为形容词作定语，as从句中的主语为比较对应项，必须省略。（或理解为as为比较代词，在从句中作主语。）

Whether the shape of the cluster was the same on the left side as on the right side. 

the same为形容词作表语，...was the same on the left as (it was) on the right side.

It's a phrase that reads the same backwards as forwards. 回文就是顺读和倒读都一样的词语（例如 mom）.

这句的read为及物动词，the same为代词作宾语 backwards为副词作方式状语。that reads the same backwards as (it does) forwards.