比较级： more ominous
最高级： most ominous

But these ominous predictions are based on computer models .

但这些不祥的预测是基于计算机模型的。

An ominous counter-example is iraq .

有个不祥的反例，伊拉克。

That is an even more ominous possibility .

这是一种更加不祥的可能性。

There are already some ominous signs .

已经出现了某些不祥的迹象。

Some comments by chinese officials carried an ominous tone .

中国官员的一些言论透露出了一种不祥的基调。