effective adj.有效的；生效的，起作用的 - 悠遊海闊天空

adj.有效的[（+against/in）][+to-v]；（法律等）生效的，起作用的[Z]

We regret to announce that Mr. Charles Appiah has resigned his position as senior sales manager, effective next monday.

1.有效的[（+against/in）][+to-v]Window screens are effective in keeping out mosquitoes. 紗窗能有效地擋住蚊子。
2.（法律等）生效的，起作用的[Z]A bill passed by congress becomes effective as soon as the President signs it. 國會通過的法案一經總統簽署立即生效。
3.給人深刻印象的，有力的That's rather an effective use of color. 那樣使用顏色效果甚佳。
4.實際的，事實上的[Z]Although there is a parliament, the army is in effective control of the country. 雖然有議會存在，但軍隊實際上控制著這個國家。
5.有戰鬥力的[Z]