The Somali robbers' ____attacks on the sea urged all nations to

The Somali robbers' ____attacks on the sea urged all nations to take immediate action.
A、fresh
B、free
C、frequent
D、fluent
【正确答案】：C
【题目解析】：考查形容词词义。四个选项均为形容词。选项A. fresh(新鲜的);选项B.free(自由的,免费的);选项C. frequent(频繁的,时常发生的);选项D. fluent(流畅的,流利的)。所以,根据句意,选C。【参考译文】索马里强盗频繁地袭击海上,敦促所有国家立即采取行动。