'in the 1980s research scientists first detected a "hole" in this above Antarctica'
the ozone layer
O.L.: in the 1980s research scientists first detected a hole in this above Antarctica
in the 1980s research scientists first detected a "hole" in this above Antarctica
in the 1980s research scientists first detected a "hole" in this above Antarctica
"O.L."
the ozone layer
"O.L."