fluid logical element

例句：

1. 1. The liquid flowed smoothlythrough the tube.
   液体流过管子时非常顺畅。
2. 2. The river is known for itsfluid currents.
   这条河以其流动的水流而闻名。
3. 3. The new software has afluid user interface.
   这款新软件有一个流畅的用户界面。