derrick base size

例句：

1. 1. The derrick was used to drillinto the ground.
   打桩机被用来钻入地面。
2. 2. The derrick was usedto lift heavy loads.
   打桩机被用来举起重物。
3. 3. The derrick wasused to level the land.
   打桩机被用来平整土地。