Topic: Subject Verb Agreement,

Best Answer Explained in Below-:

The question "----- either of you a doctor? Or----- you both engineers?" requires an understanding of subject-verb agreement and the construction of questions in English.

In the first part, "either of you," refers to a single individual from the group of two. The word "either" indicates a singular subject, which means the verb should align accordingly. Therefore, the correct form to use here is "Is," as it is the singular form of "to be." So the appropriate question becomes: "Is either of you a doctor?"

In the second part, "you both" clearly refers to two individuals, making it a plural subject. For plural subjects, we use "are," which is the plural form of "to be." Hence, the question would correctly be: "Are you both engineers?"

Thus, the complete question reads: "Is either of you a doctor? Or are you both engineers?" Hence, the correct option "D: Is/are" accurately reflects the grammatical structure necessary for this inquiry.