it has been noted that是什么从句

it has been noted that是什么从句

it has been noted that是什么从句
it has been noted that。。。是主语从句。
it has been noted that。。。
=it that。。。has been noted
主句是：it has been noted
从句是：that。。。
that从句整个作主语，因太长不适合跟it放在一起，故置于句末。