名词
中文翻译：空心
同义词：
['hollow', 'cavity', "void例句：1. The tree's trunk is hollow", 'which makes it easy to climb up.（这棵树的树干是空心的，这使得它很容易爬。）']
例句：
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1. The tree's trunk is hollow, which makes it easy to climb up.
这棵树的树干是空心的，这使得它很容易爬。
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2.The hollow space inside the shell is filled with air.
壳内的空间是空的，里面充满了空气。
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3. The hollow sound of the bell echoed through the room.
钟声空洞的声音在房间里回荡。