watermark
n
1 manufacturer's design in some types of paper, which can be seen when the paper is held against the light (某些种类的纸上印制的)水印.
2 mark that shows how high water (eg the tide or a river) has risen or how low it has fallen 水位标志(如潮水或河流的).
One foe is too many; and a hundred friends too few.
朋友成百犹觉少,仇敌一人已嫌多。
Some of the bigger firms are engaged in researches which are of such general and fundamental nature that it is a positive advantage to them not to keep them secret.