1. The flood had been caused by unprecedented rainfall.
   洪水是由于前所未有的大量降雨造成的。
2. Our school faced unprecedented difficulties.
   我们学校碰到了前所未有的困难。
3. The rate of growth was unprecedented.
   这个成长率是前所未有的。
4. Unprecedented economic growth.
   史无前例的经济增长
5. A flood of this sort is really unprecedented.
   这样大的洪水真是十年九不遇。

　1个形容词解释