And that 's not even the most troubling part .

但这还不是最令人不安的部分。

The threat to air travel from icelandic volcanos is still troubling

冰岛火山对空中旅行的威胁仍很烦人

But two questions remain troubling .

但是仍然存在着两个令人担心的问题。

Behind these sharpened conflicts lies something still more troubling .

这些尖锐冲突的背后还有更麻烦的事。

But the circumstantial evidence as noted by the fbi is certainly troubling .

但是正如fbi所指出的，这些证据自然是很令人头疼的。