Question

It is likely that有没有过去式

Answer 1

没有过去式。
It is （very）likely that从句：（很）可能；(很)可能
it 是形式主语，that 从句为真正的主语。比较：It is likely that he will go.= That he will go is likely.可能他会走。又如：It’s very likely that she’ll dance tonight. 很可能今晚她跳舞。
知识拓展：as likely as not=most/very likely很可能:As likely as not she's forgotten all about it.她很可能把这事忘得一干二净了。