If there is no gainsaying something, it is true or obvious and everyone would agree with it.
例句
However much people have criticised her style and some of her policies no one will gainsay her courage...无论人们如何强烈地批评她的处事风格和某些政策，她的勇气却无人能够否认。There is no gainsaying the fact that they have been responsible for a truly great building.不容否认的事实是，他们一手建起了一座真正伟大的建筑。