可能是这个原因（注水角度不妥）以及解决办法：

If ‘flapper is being kept up by the water flow from the refill” you will see bubbles coming into the tank from the drain seat Reset the angle of the water flow from the angle adapter so it hits the top inside of the over flow pipe. This will allow the stream of water to run down the wall of the pipe and allow the flapper to close. - See more at: http://www.fluidmaster.com/blog/toilet-flapper-will-not-close/#sthash.14x4IOpi.dp