Everything happens as if we didn’t know that deforestation is a huge problem.
She behaves as though she were not concerned by the fate of the planet.
They look as if they had been bewitched by the beauty of Guyana!
HINT
▪ Unreal assumption about the present as if / as though + simple past ▪ Unreal assumption about the past as if / as though + past HAVE + V-en