Fourier series
[计] 傅里叶级数
🧩 词语组成解析
n. 傅立叶（姓氏）；傅里叶（法国空想社会主义者, 社会改革家）
🗣️ 情景例句
I'm sorry. I missed that.
对不起，我没听清。
To stand on your hands
倒立
'He had travelled only seven miles across the Channel when his engine failed and he was forced to land on sea.
但他只在海峡上空飞行7英里，引擎就发生了故障，他只好降落在海面上。