同位语从句和表语从句是只能用that吗

同位语从句不一定只用that ,但多数情况是用 that .
I have an idea that we have dinner together.后面从句不含疑问
I have no idea whom we have dinner with.后面从句有疑问
表语从句和主语从句,宾语从句一样,看后面的从句有没有疑问,如果有,不能用that.
It is what I say.后面从句缺成分
The point is how we can deal with it.后面从句有疑问
My opinion is that we have dinner together.后面从句不含疑问,也不缺成分

高中阶段认为是的，不用在这上面钻太深，应对考试一个that 绝对够，这种题只会在完成句子里出现，记住：the fact/news that +clause+is true (同位语) the fact is that he died(表语)
the problem is how to deal with it(表语) 这些就够了！

不是的