英语语法分析

The thrust force is mainly due to the drag of the wings in the upstroke.

平衡身体阻力的推力主要由翅膀上拍中产生的阻力提供。

The peak polished rod load occurs near the bottom of the stroke with the start of the upstroke.

最大光杆负荷发生在上行冲程开始时的冲程底部附近。

Modern birds use a similar bone in flight, drawing their wings toward their bodies during an upstroke.

现代鸟类在飞行时也需要依赖这块腕骨，它们通过这块骨骼牵引翅膀以获得抬升力。