it is still cannot be ascertained that...

解答：网友自己造的这个句子，在“主句里”有2个谓语动词，属于严重违背或者违反“英语语法原则”，网友必须要知道，不管是主句还是从句里，都必须只能出现 1套“主语+谓语动词”结构。

(1)It is still can not be ascertained that(主语从句)....（出现了 is , can't be ascertained 2个谓语动词，属于严重语法错误。必须去掉一个谓语动词）

(2)It can not be ascertained if/whether(主语从句)  (正确)

It can't be ascertained if the land is still owned by the government. 不能确定这块土地是否仍属于政府所有。

(3)It is  ascertained that(主语从句) (正确)

It is ascertained that the land is still owned by the government. 现在确定这块土地是属于政府所有。