第一个是定语从句~
第二个是同位语从句~
同位语是名词性从句~简单说就是解释说明前一个名词的内容的
1 I don't know the reason why/ for which she is late.(在定语从句中做原因状语 )
只是说她迟到的原因,但还是没有说出原因的内容
eg.I don't believe the news that he gave us (定语从句)
I don't believe the news that ants could fly (同位语从句)
2 I have no Idea when he will be back .
he will be back 是when引导的同位语从句,其先行词idea则不是表示时间的名词,我没有想法(想法是针对他会不会回来的~是说明内容的)
希望帮到lz~