Help the frantic party host piece together the evening's disasters by choosing the correct verb for each question.

I need to know immediately: who brought that terrifying neon green gelatin salad to my house? Also, why did the dog bite the mailman, and how long had he been hiding under the sofa?

I need to know immediately: who brought that terrifying neon green gelatin salad to my house?

When "who" is the subject of the question, we do not use the auxiliary verb "did." We just use the past tense verb directly (who brought).

Also, why did the dog bite the mailman...

In a standard object question in the simple past tense, we use the auxiliary "did" followed by the subject ("the dog") and the base verb ("bite").

...and how long had he been hiding under the sofa?

"Had been hiding" is the past perfect continuous tense. The entire story is set in the past ("brought," "did bite"), so the hiding — which was already ongoing at that past moment — uses "had," not "has."