active center的用法和樣例：
例句
- The production of polymer in each case involves the rapid addition of monomer to a few active centres.
在各種情況下聚合物的生成都是單體對少數幾個活性中心的快速加成。 - You need your student ID to get into the student recreation center.
你要有學生證才能進入學生活動中心。 - The first one is the construction of the Oberlin Student Center.
其一，建構奧柏林學生活動中心。
