center mark的用法和樣例：
例句
- The runner reached the halfway mark in the race after 49 seconds.
比賽四十九秒鐘后賽跑選手抵達了中點(diǎn)。 - The color gradient is a smooth shading of colors from the center point of the path to the outside boundary edge of the path.
彩色漸變是從路徑的中點(diǎn)到路徑的外邊界邊緣的平滑的彩色漸變。
