Definition: having a hole or empty space inside Level: C2
这个玩具是用一根空心的管子制成的。
The toy was made from a ___hollow tube.
我们在那根空心的原木里发现了一个鸟巢。
We found a bird's nest inside the ___hollow log.
他的承诺听起来空洞且不真诚。
His promise felt ___hollow and insincere.
