一个英语从句的问题It is never a good sign when the market drops 380 p

一个英语从句的问题
It is never a good sign when the market drops 380 points on the day you give your first major policy address as Treasury Secretary.
1、这个it is是形式主语的句型吗?
2、when是引导状语从句吗?
3、you give your first major policy address as Treasury Secretary.是不是一个省了引导词的从句,哪是什么从句?省了什么引导词?