Which sentence is correct?

It does sound awkward, but the subject and verb of the sentence are "They" and "know". "Who each other is" is a noun clause used as the direct object. "Each other" is singular. Therefore "each other is" is correct. Can you rephrase the sentence to avoid this? They know each other; they are aquainted, etc.

Are, b/c you're talking about more than one person, the word needs to be plural as well...but I think there's a better way to phrase it than either one of those.

2) They know who each other is....I think. because the pronoun each is singular so the verb to be (is) has to be in singular form also.

Each knows the other.

They know each other.

They both know each other.

Each of them knows the other.

Both of them know each other.

they know who each other are.........bcuz the second one doesn't agree with the tense of the sentence(past,present,future).

The first one is correct.

Why not

THEY KNOW EACH OTHER.

They know who each other are.

They is plural--- are is plural.

neither