Did you hear someone knocking at the door.和 Did you hear someone was knocking at the door. 第

Did you hear someone knocking at the door.和
Did you hear someone was knocking at the door.
第二句多个was，都对吗？？？

语法上两种都可以，习惯上用第一种。

hear someone doing sth 是动宾+宾补的结构，类似see someone doing sth
第二种是宾语从句的结构， hear that...

您好！ 同义句为：there is someone knocking at the door. 意思是：有人敲门。   望您采纳，谢谢您的支持！