Question

He was nearly drowned once.-When was ( )? -( ) was in 1998 ( ) he was in middle school.急!

-He was nearly drowned once.
-When was ( )?
-( ) was in 1998 ( ) he was in middle school.
我知道答案是that it when
但是为什么最后一个when啊?这不是强调句吗?那应该是that啊?!
于是我看到一种解释是:答句属于变相的强调句，当表示时间的时候，强调句中的that可以换成when，所以去掉it was...when...再调整一下语序，就是 He was in middle school in 1998 .
但是我看到另一种解释是:when引导的是定语从句。如果加逗号，就是非限制性定语从句。时间状语从句是用来修饰句子的谓语动词的，表示动作发生的时间。例如：
It happened when I was living in the country.
这事发生在我住在农村的时候。
哪种解释才是正确的啊!求外国佬帮帮忙啊!

Answer 1

这是强调句的一种省略。完整形式是：It was in 1998 when he was in middle school that he was nearly drawned . 强调句型中套有定语从句是高考中常有的。

Answer 2

这句话是个强调句和定语从句的结合，而且是个省略句。全句应该是：
It was in 1998 when he was in middle school that he was nearly drowned.