This is about subject-verb agreement.

How should I re-write this sentence:
"Either the interviewer or the committee members usually begins by asking simple questions about your background."

"Each of the instructors are attending the conference next weekend."

How should I write these two sentences.

The first sentence is correct; the second is wrong.

Either and each are both singular subjects and take singular verbs.

To maintain subject-verb agreement, you can re-write the sentences as follows:

1. "Either the interviewer or the committee members usually begin by asking simple questions about your background."
Explanation: When using either/or constructions, the verb should agree with the subject closer to it, which in this case is "committee members" (plural). Therefore, the singular verb "begins" should be changed to the plural form "begin."

2. "Each of the instructors is attending the conference next weekend."
Explanation: When using "each of," the verb should agree with the singular noun that follows it. Therefore, the plural verb "are" should be changed to the singular form "is" to agree with "each."

To ensure subject-verb agreement in the given sentences, follow these guidelines:

1. "Either the interviewer or the committee members usually begins by asking simple questions about your background."
When using "either/or" or "neither/nor" constructions, the verb should agree with the subject closest to it. In this case, the subject closest to the verb is "committee members," which is plural. Therefore, the correct re-write would be:
"Either the interviewer or the committee members usually begin by asking simple questions about your background."

2. "Each of the instructors are attending the conference next weekend."
When using the phrase "each of" (or "every," "any," or "either"), the verb should be singular as it refers to each individual separately. Therefore, the correct re-write would be:
"Each of the instructors is attending the conference next weekend."