可想而知的英文：
be imaginable

Here the case was very different, as might have been expected from the duke’s love of the bizarre
而这里的情况大不相同，因为这位王爷就爱别出心裁，其余可想而知了。

It is an imaginative tale.
这是个虚构的故事。

Everthing went according to imagine.
一切都按计划进行（或实现）了。

They are imagining to rob a bank.
他们正在策划抢银行。

Fairy tales are imaginative.
神仙故事是幻想出来的。

He is an imaginative boy.
他是一个喜欢想象的孩子。