it is not yet eight o'clock when he arrived home.什么从句?

问题描述:

it is not yet eight o'clock when he arrived home.什么从句?
是状语从句还是定语从句?为什么?
it is 1999 when i met him是定语从句
it is in 1999 that i met him是强调句型
那it is in 1999 when i met him 就不可以吗,不能理解为时间状语从句吗?when i met him,it is in 1999.

it is not yet eight o'clock when he arrived home.是状语从句,不过不是it is 而应该是It was...it is 1999 when i met him是状语从句,同样is 应该改为was.再如:It was nine o'clock when I got there.我到那里时...