Central difference operator
[计] 中心差分算子
🧩 词语组成解析
🗣️ 情景例句
Sam, would you come in, please?
Sam，请进来一下， 好吗？
No gains without pains.
不劳无获。
The actual figure was made of copper supported by a metal framework which had been especially constructed by Eiffel.
这座雕像的主体是用铜制成的，由艾菲尔特制的金属框架支撑着。