A year before I believed we (can) stay for a long time是什么句式

A year before I believed we (can) stay for a long time是什么句式
A year before I believed we (can) stay for a long time是什么句式

A year before I believed we (can) stay for a long time是什么句式
句式?
时间状语从句?

状语从句

晕死。。
宾语从句
名词性从句一种
a year before 是状语