Tom can't get into the room because he __(lost)the key to the door.

Tom can't get into the room because he __(lost)the key to the door.
Tom can't get into the room because he __(lost)the key to the door.

Tom can't get into the room because he __(lost)the key to the door.
has lost
过去的事对现在造成影响用现在完成时

lost

has lost
有不明白的地方再问哟，祝你学习进步，更上一层楼！ (*^__^*)