n.底部，下侧，底面，下表面

原形：underside复数：undersides

The underside of the bridge was covered in graffiti.
桥的下面布满了涂鸦。
The car had a dent on its underside after hitting a pothole.
这辆车在撞到坑洼后底部有凹痕。
The insect's underside was a vivid shade of red.
昆虫的下腹部是鲜艳的红色。
The boat rode low in the water, revealing the underside of its hull.
小船在水中下沉，露出了船底。
The turtle flipped onto its underside, unable to right itself.
海龟翻了个身，无法翻身过来。
The sofa had a storage compartment beneath its underside.
沙发的下面有个储物空间。
The skier caught an edge and crashed, landing on his underside.
滑雪者滑倒了，摔倒时身体朝下。
The building's underside was illuminated at night, creating a spectacular sight.
建筑物的底部在夜晚被照亮，形成了一道壮观的景色。
The spacecraft re-entered the Earth's atmosphere, its underside glowing from the heat.
航天器重新进入地球大气层，其底部因热量而发光。
The caterpillar's underside had rows of tiny legs for gripping surfaces.
毛毛虫的下面有一排排小脚用来抓握表面。