Do I use has been or have been?

When writing this sentence "Mrs. Jones, and many other teachers, _____ been grading papers." Do I use have or had, and why?

I agree with user 772922, but here is a fuller explanation of the grammar rules.

"Have" and "has" are conjugations of the auxiliary verb used in the present perfect tense. The choice of which one to use has nothing to do with the tense. It is simply dictated by the subject of the verb -- in other words, "who" has or have or had been.

The present perfect tense is used to convey an action that began in the past and continues in the present.

Here is the conjugation of the verb "to be" in the present perfect tense: I have been We have been You have been He/She/It has been They have been

The past perfect tense is used to convey something that happened in the past, a past that occurred before another, later action in the past that you happen to be discussing, as in, "I had made the cookies before we ate."

Here is the conjugation of the verb "to be" in the past perfect tense: I had been We had been You had been He/She/It had been They had been

And that's the rule!

Regarding the original question, it does seem that the subject is not the singular Mrs. Jones, but a plural "they" that includes both Mrs. Jones and a lot of other teachers. So you would use either "have been" or "had been" (but not "has been"). The choice is up to the author, depending on which tense is to be conveyed.

I hope that's helpful.

The site's rules ask for sources. Lots of sources, including the Chicago Manual of Style and a ream of English grammar textbooks I was given throughout my K-12 education, including the once ubiquitous Heath Handbook of English.