— How long has the train been away?— Sorry. I don't know. By the time I got here, the train ________.
把下列词语补充完整。
____然____同 张____结____
走____串____ 明月____
灯____通____ 彻夜____
①BM与ED平行;
②CN与BE是异面直线;
③CN与BM成60°角;
④DM与BN垂直.
以上四个命题中,正确命题的序号是( )