constant cross-section

例句：

1. 1. The temperature isconstant throughout the day.
   温度在整个白天都是恒定的。
2. 2. The river flows through aconstant landscape.
   河流穿过一片不变的风景。
3. 3. Theconstant rain made it difficult to work outside.
   持续的雨使得在外面工作变得困难。