unprovoked

形容词 unprovoked:

1. occurring without motivation or provocation- F.D.Roosevelt
   同义词：motiveless, wanton

1. The boys' attack on the old woman was quite unprovoked.
   那帮男孩对老妇人的袭击完全是无来由的。
2. I ask that the Congress declare that since the unprovoked and dastardly attack by Japan on Sunday December7,1941, a state of war has existed between the United States and the Japanese Empire.
   我要求国会宣布：由于日本在1941年12月7日星期日对我国无故进行卑鄙的袭击，美国同日本已经处于战争状态。
3. An unprovoked attack.
   未经挑衅就发动的进攻