Sub-Verb agreement?

Question

I can't seem to get this for some reason. How can you tell wich form of a verb is singular and which is plural?

Example: (Has, Have) either of the owners expressed interest? the answer is Has, but to me have sounds better. Is there a general rule I can follow to avoid such mistakes?

Answer 1

I think you just have to memorize them and listen to how they sound in a sentence. They usually sound awkward if the wrong one is used, For instance: "It are green" sounds awkward as opposed to "It is green". Or, "They is large." as opposed to "They are large."