Select all that apply. In which scenarios should a past-simple wh-question use did?
The guard is known; the visitor whom the guard admitted is unknown.✓پاسخ درست
The person who rang the bell is unknown.
The team is known; the day when the team departed is unknown.✓پاسخ درست
The object that cracked the window is unknown.
توضیح
Did is needed when the wh-expression replaces an object or a time expression and a known subject remains in the question. It is not needed when the unknown person or thing is itself the subject that performed or caused the action.