it's a pity that you can't join us 这句that引导的是什么从句?

it's a pity that you can't join us 这句that引导的是什么从句?
it's a pity that you can't join us 这句that引导的是什么从句?

it's a pity that you can't join us 这句that引导的是什么从句?
这是由it这个形式主语引导的同位语从句,其真正的主语是that后面的句子!

定语从句修饰pity

同位语 that 的从句 和pity 同一意思