hollow

n. 洞,窟窿,山谷
a. 空的,虚伪的,空腹的
v. 形成空洞,挖空

This tree looks high and strong but actually its trunk is hollow.

这棵树看起来又高又壮，实际上树干是空的。

His protests on human rights sound hollow.

他就人权问题提出的抗议听来很空洞。