knocking at the door before entering ,please 这句话哪里了

____ at the door before entering,please knock at the door before entering please这句话是时间状语从句吗? knock at the door before entering please句中只有KNOCK AT 一个动词?en 英语改错 “Please knock the door before entering.” (1)Please do not e_____ before knocking on the door. Don't come in before knocking at the door. Please do not e_____without knocking at the door. Please do not ------without knocking at the door We should k____at the door before entering. 同义句转换 Before entering the office ,he knoched at the door.Bef ——at the door before you enter my room A knock B knocking Ck who is knocking at the door?