flat thin tubesheet

例句：

1. 1. The floor is very flat andeasy to clean.
   地板非常平坦，容易清洁。
2. 2. The table is flat enough for alarge group of people.
   桌子足够大，可以容纳一大群人。
3. 3. Theroof of the house isflat, which makes it easyto access the attic.
   房子的屋顶是平的，这使得进入阁楼变得很容易。