MaryhadtogotoBeijingonJune15,__

发布时间：2020-07-11 04:19:54

Mary had to go to Beijing on June 15, ________ happened to be her only son's birthday．













A.which












B.when











C.then











D.it

网友回答

A
以上问题属网友观点，不代表本站立场，仅供参考！