1.When an object is immersed in the water, the water exerts an upward force called upthrust on the object in question.

当一物体浸入水中时，水会对该物体施加一向上的力，即向上的推力。

2.And it was near the island's southern tip–the tip jutting into the harbor–that the colossal upthrust had been greatest.

而且，岛屿的南端——伸入港口的尖端——，巨的上升推力最。机翻