It is generally considered that air pollution is ______ danger to ______ nature.
Patience is a kind of quality — and that is ___A___ it takes to do anything well.
They lost their way in the forest, and _______ made matters worse was that night began to fall.
He told me the news, believe it or not, ______ he had earned $1 000 in a single day.
I think, though I could be mistaken, ______ she liked me.
Everyone knows, perhaps except you, _______ your girl-friend is a cheat.