Concave shape的用法和樣例：
例句
- The cloven hooves are sharp edged, elastic and concave.
蹄鋒利，呈凹形，富有彈性。 - This article has described expanding method for repairing the concave retaining ring caused by the hydraulic bulging.
詳細介紹了用擴沖法對液壓脹形出現凹形的護環(huán)進(jìn)行修復的方法。
