troubling layer

基本解释

The most troubling of the short-lived HFCs were invented to replace chlorofluorocarbons, refrigerants that were thinning the ozone layer in the upper atmosphere, and were also a major warming agent.
其中最短命的氫氟碳化郃物，被發明取代氯氟烴，制冷劑可以稀釋高層空氣中的臭氧層，同時也是主要的陞溫劑。

So is that not troubling that he got through that first layer?
WHITEHOUSE: Press Briefing
Troubling for more traditional regional banks a layer or two down from the very biggest U.S. banks are rules that may force them to raise capital and, bankers argue, restrict lending.
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More troubling are security issues, since most safeguards work in a different layer of a network from the data-hauling Ethernet layer of 802.11.
FORBES: Mr. and Mrs. Network