不可以，用it做形式主语，that引导主语从句
不能去掉，因为It在这里是形式主语，that引导的句子就是It
不可以。同位语从句
it is concluded that_有道词典it is concluded that结论是......更多释义>>[网络短语]It is concluded that 结论是It is concluded that... 结论是...详细用法>>
