negative refraction的用法和样例：
例句
- To understand how negative refraction can arise, one must know how materials affect electromagnetic waves.
要了解负折射如何发生，我们必须先知道材料如何影响电磁波。 - The tunability was analysed at the specified frequency and a large tunable range of the negative refraction is achieved.
发现负折射角度有较大的范围，适合作为可调折射角之光学元件。
