It is highly unlikely that she'll be late.

她迟到的可能性极小。

It seems highly unlikely that she ever existed.

看来很有可能压根儿就没有过她这么个人。

I think it highly unlikely that I'll get the job.

我认为我得到这份工作的可能性极小。

It is theoretically possible for him to overrule their decision, but highly unlikely.

按理说他可以否定他们的决定，但是可能性很小。

This is highly unlikely.

这是极不可能的。