那座桥在没有任何先兆的情况下坍塌了。

The bridge collapsed without (any) warning.

《牛津词典》

然而，这种药物没有明显减少不管有无先兆的偏头痛天数。

However, thedrug did not significantly reduce the total number of migraineheadache days with or without aura.

youdao

几个月前，我了解到的关于看到先兆的技巧，决定开始训练我的这种能力。

I knew about the techniques of seeing auras and a couple of months ago I decided to start practising my aura sight.

youdao