洞门【tunnel portal】指的是为保持洞口上方及两侧路堑边坡的稳定，在隧道洞口修建的墙式构造物。
这个洞是巢的门。
每个房间后面都有一个55加仑的鼓形炉，前面有一个门，后面有个带两个管道的烟囱洞。
Behind each chamber is a 55-gallon-drum stove with a door on the front and a chimney hole with two pipes in the back.
爱丽丝打开了门，发现门外是一条小走廊，比老鼠洞还小。她跪下来，顺着走廊往外望去，看见一个你从来未曾见过的美丽的花园。
Alice opened the door and found that it led into a small passage, not much larger than a rat-hole: she knelt down and looked along the passage into the loveliest garden you ever saw.
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