Nearly 50 years ago, three chemists named Mario Molina, Sherwood Rowland and Paul Crutzenfound evidence that chlorofluorocarbons, chemicals known as CFCs and released from aerosolsprays, were weakening the ozone layer that functions as the earth's natural sunscreen__11__humans, animals and plants from harmful radiation. The case for global action became__12__urgent in 1985 when a British team discovered a hole in the ozone layer above Antarctica, followedby confirmation by NASA scientists of a connection between the hole and CFCs. With the rest ofthe world and even industry __13__, the result was the 1987 Montreal Protocol, a landmarkagreement banning chlorofluorocarbons and other __14__chemicals. End of story? Not quite. As ithappened, the ozone-friendly replacements for the CFCs, known as hydrofluorocarbons (HFCs),turned out to be distinctly unfriendly to the climate. Thus, in 2016, the Montreal signatoriesreconvened in Kigali, Rwanda, and agreed to amend the original protocol to __15__HFCs and findsubstitutes that are more friendly to the atmosphere.
【題組】11.
(A) prohibiting
(B) protecting
(C) providing
(D) proposing