Is every sentense below normal? Or which one is incorrect?<br/><br/>1 I <font color="#800080">was watching</font> TV in my room about an hour when I heard a knock on the door.<br/><br/>2 I <font color="#ff1493">had been watchin</font>g TV in my room for about an hour when I heard a knock on the door.<br/><br/>3 I <font color="#ff1493">had been watching</font> TV in my room for about an hour <font color="#800080">before</font> I heard a knock on the door.<br/><br/> Thank you for your kindness in advance.