“平缓的”用英语怎么说？

霍顿向外望去，肥沃的谷地和平缓的丘陵尽收眼底。Horton looked out over a panorama of fertile valleys and gentle hills.大平原上起初地势偶尔有些平缓的起伏.The foothills began as gentle rolls in the plain.但在倾角小,地形平缓的情况下,放大垂直比例尺是有用的.An exaggerated vertical scale is ...