gravity darn的用法和樣例：
例句
- It also includes a consideration of possible alternatives, such as a concrete gravity dam or an earth-fill embankment dam.
還要考慮到可能的備選方案，比如是選擇混凝土重力壩還是選擇填土築堤大壩。 - Engineering structures falling in this category are gravity dams with foundations, slopes and embankments, etc.
屬於這種範疇的工程結構為帶有基礎的重力壩，斜坡和路堤等。
