before可以引导表语从句吗？

Question

There was a time, actually—you’ll see this in the memories later—when flesh was many different colors. That was before we went to Sameness. Today flesh is all the same, and what you saw was the red tones.

在上面这段话中，That was before we went to Sameness.这句话中的before we went to Sameness是表语从句吗？ 因为所有语法书中都说明的是before作为从属连词引导的是状语从句。到底该如何理解这句话的语法成分呢？

Answer 1

表语从句定义：在一个 复合句中，从句作的是主句的表语成分。
A
The problem is puzzling.
这个问题令人困惑。
主语+ 连系动词+形容词作表语
The problem is when we can get a pay rise.
问题是什么时候我们可以得到加薪。
主语+连系动词+ 句子作 表语（表语从句）
B
连接表语从句的 连接词有：that, what, who, when, where, which, why, whether, how, whoever，whichever ，whatever等。还有如because, as if, as though等。本回答被网友采纳

Answer 2

可以怎么用，就是连词+句子追答

这么