The little boy did not like the look of the barking dog.
"It's all right," said a gentleman, "don't be afraid.
Don't you know the proverb: Barking dogs don't bite?"
"Ah, yes," answered the little boy. "I know the proverb, but does the dog know the proverb, too?"
bark 吠叫 [barking]是[bark]的现在分词形式