（在祈使句中）before enter the house 还是 before entering the house 还是 before entered the house

（在祈使句中）before enter the house 还是 before entering the house 还是 before entered the house Koock at the door before enter the room 中enter要不要变形? 在语文中什么是祈使句? 在英语中怎么判断祈使句?怎样运用祈使句? 祈使句能容纳两个谓语吗?例句：_Knock_ at the door before you enter my room,please.Knock 和 enter 不是两个谓语吗?这个句子里为什么不能用Knocking? please在祈使句中一定要在句首吗? 请问在英语中什么是祈使句 some在祈使句中变any吗 Mike did not see anybody enter the building before ten(改为同义句）Nobody_ _ _ _the building before 祈使句中please前需要加逗号么please在祈使句中放句尾时候要+,么 knock at the door before entering please句中只有KNOCK AT 一个动词?enter为什么不是? 在语文中,把一个句子改为祈使句,怎么改? 英语中什么是祈使句? 改错.Knock before you enter into the room. you must ____(knock)on the door before you enter what should we do before we enter a house in always knock on the door before you enter before you e---- the house 用enter 还是entered