When referring to a class of things, especially countable things, I am always confused about singular noun and plural nouns. For example:
Dogs are the most lovely animal in the world.
The most lovely animal in the world is dogs.
I know both sentences are grammatical correct because verbs only need to agree with the subject. However, those sentences sound awkward because of mixing singular noun and plural nouns.
So what is the best way to refer a class of countable things?
I have been suggested that I can use "the dog" to refer all dogs. So can the + a singular countable always represent a class of things?