It is suggesting that the rain is coming down very heavily. The rain is a deluge, soaking everything with large, heavy, water-filled droplets quickly falling. The is based off the original idiom "It's raining cats and dogs" to indicate that it is pouring rain. It takes the hyperbole one step farther to add heavier and larger animals to show the amount of rainfall.
it is a gerund because it acts like a noun and ends in -ing
Answer: The word gymnasium is originally a Latin word
Show how much he was frightened he was.
