closed core的用法和樣例：
例句
- The first step is to read the contents of a punch card into a core.
第一步是把穿孔卡的內容讀入磁心。 - This paper describes a series of practical equations for the design of ferrite core inductors, and verifies them by measuring and simulating.
整理出一套工程實(shí)用的鐵氧體磁心電感設計公式，并通過(guò)實(shí)際測量和計算機仿真對其作了驗證。
