the day__John shall never forget is the one __he joined the army 1.when/in which 2.which/when 答案為2,請問為第一個空格是用which?

1. John shall never forget the day. （日期，用關係代名詞which）
2. He joined the army at that day. （時間點，用關係副詞when）

The day "which John shall never forget" ....
day是「先行詞」，接受限定性質的形容詞子句修飾，所以前面用定冠詞the的限定。關係代名詞which兼作形容詞子句動詞forget的「受詞」，帶出形容詞子句。

... the one when he joined the army.
one是「先行詞」，接受限定性質的形容詞子句修飾。關係副詞表when示at that time（述部的修飾語），帶出形容詞子句。

The day [which] John shall never forget is the one [when] he joined the army.