I learned the word "either" is singular. Is the sentence "Have either of you" gramatically correct?
This is a really great question. "Either" is singular and takes the singular verb. Technically, "has either of you" is the correct answer. However, conventional usage means that either + the plural verb form is more commonly used. Thus, "has either of you" is grammatically correct, but "have either of you" is more commonly used and accepted amongst English speakers. Ex. Have either of you seen my cat? Ex. Has either of you seen my cat?