flat transparency

例句：

1. 1. The table is very flat and easy to clean.
   这张桌子非常平坦，很容易清洁。
2. 2. The floor is flat and smooth.
   地板是平坦光滑的。
3. 3. The roof of the house is flat, which makes it easier to insulate.
   房子的屋顶是平的，这使隔热更容易。