dual-cone的用法和樣例：
例句
- For each double cone, the opposite pulls from two parts of the sphere exactly cancel.
就每一雙錐面來說，球殼的兩個部分所產生的相反引力正好對消。 - The die and eqiupment of internal pressurized expanding retaining rings and double cone wedge-reaming die were also studied.
對內增壓擴脹護環的裝置和雙錐面楔塊擴孔模具進行了研究。
