A frog croaked, at a time of year too late for frogs.
"A cat has nine lives but a frog croaks every day."
Near me was a rain barrel fall of frogs croaking.
There, like that, that's it 11 hear frogs croaking in the swamp outside my window.
That depends on whether global or local causes are making the frogs croak.
However many frogs croak, the result will only ever be a croaking sound.
The frog croaked in the rain-barrel again, and the door closed behind him.
A frog croaked from the side of the lake.
Frogs croaked, and several times we heard great roarings in the distance.