Prefading
预调节
🗣️ 情景例句
I hope you're all enjoying the exhibition.
我希望你们都喜欢这个展览
I want to get cigarettes.
我要买香烟。
and a period (which is the time it takes a wave crest to travel one wave length).
和周期（浪峰走过一个波长所需的时间）。