- Have you really been to visit the Bird’s Nest in Beijing?　 -I it last summer vac

网友回答

A. do visited
B. do visit
C. did visited
(答案→)D. did visit
解析：句意：上文，你确实参观了北京的鸟巢了吗？下文，在上个暑假，我确实参观了。对于谓语动词进行强调，就是在动词原形之前加上相应的助动词。根据时间状语last summer vacation，可知是一般过去时，故要用相应的助动词did,选D。