There had been an incident which was perturbing.
曾经出了一点令人不安的事故.
辞典例句
"distressing (or disturbing) news"
"lived in heroic if something distressful isolation"
"a disturbing amount of crime"
"a revelation that was most perturbing"
"a new and troubling thought"
"in a particularly worrisome predicament"
"a worrying situation"
"a worrying time"