re·ac·tive /riˈæktɪv/
  (a.)反動的,反應性的,反衝的
  re·ac·tive /rɪˈæktɪv/ 形容詞
  反應的,活性的,反作用的,電抗的,無功的,反應的
  reactive
  反應
  Re·act·ive a.  Having power to react; tending to reaction; of the nature of reaction. -- Re*act*ive*ly, adv. -- Re*act*ive*ness, n.
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  reactive
       adj 1: participating readily in reactions; "sodium is a reactive
              metal"; "free radicals are very reactive" [ant: unreactive]
       2: tending to react to a stimulus; "the skin of the geriatric
          is less reactive than that of younger persons"- Louis Tuft