free neutron

例句：

1. 1.The scientists are trying to understand the behavior of free neutrons in the nucleus.
   科学家们正在尝试理解自由中子在核内的行为的。
2. 2. Free neutrons can be used as a source of energy for nuclear reactors.
   自由中子可以作为核电站的能量来源。
3. 3. The research on free neutrons has led to important discoveries in nuclear physics.
   对自由中子的研究表明，在核物理领域取得了重要的发现。