Complete the sentence with the correct form of the verb in brackets: "The east wing of the gallery has been ____ (shut) since the roof started leaking."

توضیح

Has been calls for a past participle, and this verb belongs to the invariant group whose base, past simple and participle are all spelled the same way, so nothing is added. Shutted would force the regular -ed ending onto a verb that never accepts it, and the unchanged spelling here is the genuine participle, not a base form left in place by accident.