Question

英语语法、从句，详见问题补充。

He is not the person who was ten years ago.
He is not who he was ten years ago.
这两句话都对吗？前一个是定语从句，后一个是表语从句？这两句话的中文意思相同吗？

谢谢。

Answer 1

The problem is puzzling.
这个问题令人困惑
主语+连系动词+形容词作表语

主语 连系动词一个句子作表语 --- 表语从句
表语从句一定要用陈述语序。
False: The question is when can he arrive at the hotel. （错）
Right: The question is when he can arrive at the hotel.

不像宾语从句，在有表语从句的复合句中，主句时态和从句时态可以不一致。
Right: The question is who will travel with me to Beijing tomorrow.
Right: The question is why he cried yesterday.

定语从句是由关系代词或关系副词引导的从句，其作用是作定语修饰主句的某个名词性成分，相当于形容词，所以又称为形容词性从句，一般紧跟在它所修饰的先行词后面。
He is not the person who was ten years ago

the person 就是先行词
至于意思差异不大

Answer 2

两句语法都对，但通常只用第二种说法，第一句表达不清，可以换成
He is not the person that he was ten years ago.

Answer 3

是的，这两句话都正确！
第一句是定语从句，who充当从句的主语成分
第二句是表语从句，he is a jerk！这里jerk就是这句话的标语成分。而这句的who做表语从句的连接词。