It is high time they started out是什么从句?

It is high time that they started out.他们该动身了.It is high time It is high time that they started out.他们该动身了.请问这是定语从句 强调句还是主 It is high time that they started setting off on a trip ,这句话 it is high time that...是什么从句? it is a pity that...是什么从句? it is high time 后面接从句是什么时态 还有相关的关于Time的从句吗是用什么时态? It is high time that +从句,前面的如何翻译? It is high time it is high time的high是什么意思 it is high time to it is high time that . When they see birds fly high out to the sea ,they know it is 请问1．It is high time that we ＿．选started还是should have satrted?